[AIRFLOW-406] Sphinx/rst fixes

Dear Airflow Maintainers,

- Fix some syntax errors in our sphinx/rst docstrings, which appears on pythonhosted.org
- Move `xcom_push` documentation from constructor to class docstring
- Rewrite some copy in `HivePartitionSensor` and `NamedHivePartitionSensor` docstrings
- Fix `AirflowImporter` docstring that seems to have been automatically search-and-replaced

Closes apache#1717 from zodiac/xuanji/fix_documentation

airflow/contrib/operators/bigquery_check_operator.py

@@ -25,8 +25,9 @@ class BigQueryCheckOperator(CheckOperator):
     values return ``False`` the check is failed and errors out.
 
     Note that Python bool casting evals the following as ``False``:
-    * False
-    * 0
+
+    * ``False``
+    * ``0``
     * Empty string (``""``)
     * Empty list (``[]``)
     * Empty dictionary or set (``{}``)

airflow/hooks/druid_hook.py

@@ -165,8 +165,9 @@ def load_from_hdfs(
             intervals, num_shards, target_partition_size, metric_spec=None, hadoop_dependency_coordinates=None):
         """
         load data to druid from hdfs
-        :params ts_dim: The column name to use as a timestamp
-        :params metric_spec: A list of dictionaries
+
+        :param ts_dim: The column name to use as a timestamp
+        :param metric_spec: A list of dictionaries
         """
         task_id = self.send_ingest_query(
             datasource, static_path, ts_dim, columns, metric_spec,

airflow/operators/bash_operator.py

@@ -31,6 +31,9 @@ class BashOperator(BaseOperator):
     :param bash_command: The command, set of commands or reference to a
         bash script (must be '.sh') to be executed.
     :type bash_command: string
+    :param xcom_push: If xcom_push is True, the last line written to stdout
+        will also be pushed to an XCom when the bash command completes.
+    :type xcom_push: bool
     :param env: If env is not None, it must be a mapping that defines the
         environment variables for the new process; these are used instead
         of inheriting the current process environment, which is the default
@@ -50,10 +53,7 @@ def __init__(
             env=None,
             output_encoding='utf-8',
             *args, **kwargs):
-        """
-        If xcom_push is True, the last line written to stdout will also
-        be pushed to an XCom when the bash command completes.
-        """
+
         super(BashOperator, self).__init__(*args, **kwargs)
         self.bash_command = bash_command
         self.env = env

airflow/operators/check_operator.py

@@ -30,8 +30,9 @@ class CheckOperator(BaseOperator):
     values return ``False`` the check is failed and errors out.
 
     Note that Python bool casting evals the following as ``False``:
-    * False
-    * 0
+
+    * ``False``
+    * ``0``
     * Empty string (``""``)
     * Empty list (``[]``)
     * Empty dictionary or set (``{}``)

airflow/operators/presto_check_operator.py

@@ -25,8 +25,9 @@ class PrestoCheckOperator(CheckOperator):
     values return ``False`` the check is failed and errors out.
 
     Note that Python bool casting evals the following as ``False``:
-    * False
-    * 0
+
+    * ``False``
+    * ``0``
     * Empty string (``""``)
     * Empty list (``[]``)
     * Empty dictionary or set (``{}``)

airflow/operators/sensors.py

@@ -245,10 +245,11 @@ class NamedHivePartitionSensor(BaseSensorOperator):
 
     :param partition_names: List of fully qualified names of the
         partitions to wait for. A fully qualified name is of the
-        form schema.table/pk1=pv1/pk2=pv2, for example,
+        form ``schema.table/pk1=pv1/pk2=pv2``, for example,
         default.users/ds=2016-01-01. This is passed as is to the metastore
-        Thrift client "get_partitions_by_name" method. Note that
-        you cannot use logical operators as in HivePartitionSensor.
+        Thrift client ``get_partitions_by_name`` method. Note that
+        you cannot use logical or comparison operators as in
+        HivePartitionSensor.
     :type partition_names: list of strings
     :param metastore_conn_id: reference to the metastore thrift service
         connection id
@@ -312,17 +313,17 @@ class HivePartitionSensor(BaseSensorOperator):
     """
     Waits for a partition to show up in Hive.
 
-    Note: Because @partition supports general logical operators, it
+    Note: Because ``partition`` supports general logical operators, it
     can be inefficient. Consider using NamedHivePartitionSensor instead if
     you don't need the full flexibility of HivePartitionSensor.
 
     :param table: The name of the table to wait for, supports the dot
         notation (my_database.my_table)
     :type table: string
     :param partition: The partition clause to wait for. This is passed as
-        is to the metastore Thrift client "get_partitions_by_filter" method,
-        and apparently supports SQL like notation as in `ds='2015-01-01'
-        AND type='value'` and > < sings as in "ds>=2015-01-01"
+        is to the metastore Thrift client ``get_partitions_by_filter`` method,
+        and apparently supports SQL like notation as in ``ds='2015-01-01'
+        AND type='value'`` and comparison operators as in ``"ds>=2015-01-01"``
     :type partition: string
     :param metastore_conn_id: reference to the metastore thrift service
         connection id

airflow/utils/helpers.py

@@ -177,13 +177,15 @@ def f(t):
 class AirflowImporter(object):
     """
     Importer that dynamically loads a class and module from its parent. This
-    allows Airflow to support `from airflow.operators.bash_operator import
-    BashOperator` even though BashOperator is actually in
-    airflow.operators.bash_operator.
+    allows Airflow to support ``from airflow.operators import BashOperator``
+    even though BashOperator is actually in
+    ``airflow.operators.bash_operator``.
 
     The importer also takes over for the parent_module by wrapping it. This is
     required to support attribute-based usage:
 
+    .. code:: python
+
         from airflow import operators
         operators.BashOperator(...)
     """