[AIRFLOW-1442] Remove extra space from ignore_all_deps generated command

Fix extra whitespace in the ignore_all_deps arg
which was causing commands to fail.

Closes apache#2468 from aoen/ddavydov--
fix_ignore_all_deps_extra_space

airflow/models.py

@@ -934,7 +934,7 @@ def generate_command(dag_id,
         cmd.extend(["--mark_success"]) if mark_success else None
         cmd.extend(["--pickle", str(pickle_id)]) if pickle_id else None
         cmd.extend(["--job_id", str(job_id)]) if job_id else None
-        cmd.extend(["-A "]) if ignore_all_deps else None
+        cmd.extend(["-A"]) if ignore_all_deps else None
         cmd.extend(["-i"]) if ignore_task_deps else None
         cmd.extend(["-I"]) if ignore_depends_on_past else None
         cmd.extend(["--force"]) if ignore_ti_state else None