[FLINK-3667] refactor client communication classes

- ClusterDescriptor: base interface for cluster deployment descriptors
- ClusterDescriptor: YarnClusterDescriptor

- ClusterClient: base class for ClusterClients, handles lifecycle of cluster
- ClusterClient: shares configuration with the implementations
- ClusterClient: StandaloneClusterClient, YarnClusterClient
- ClusterClient: remove run methods and enable detached mode via flag

- CliFrontend: remove all Yarn specific logic
- CliFrontend: remove all cluster setup logic

- CustomCommandLine: interface for other cluster implementations
- Customcommandline: enables creation of new cluster or resuming from existing

- Yarn: move Yarn classes and functionality to the yarn module (yarn
  properties, yarn interfaces)
- Yarn: improve reliability of cluster startup
- Yarn Tests: only disable parallel execution of ITCases

This closes apache#1978

flink-batch-connectors/flink-avro/src/test/java/org/apache/flink/api/avro/AvroExternalJarProgramITCase.java

@@ -19,19 +19,12 @@
 package org.apache.flink.api.avro;
 
 import java.io.File;
-import java.net.InetAddress;
 
-import org.apache.flink.api.common.Plan;
-import org.apache.flink.client.CliFrontend;
-import org.apache.flink.client.RemoteExecutor;
-import org.apache.flink.client.program.Client;
-import org.apache.flink.client.program.JobWithJars;
+import org.apache.flink.client.program.ClusterClient;
 import org.apache.flink.client.program.PackagedProgram;
+import org.apache.flink.client.program.StandaloneClusterClient;
 import org.apache.flink.configuration.ConfigConstants;
 import org.apache.flink.configuration.Configuration;
-import org.apache.flink.optimizer.Optimizer;
-import org.apache.flink.optimizer.plan.FlinkPlan;
-import org.apache.flink.optimizer.plan.OptimizedPlan;
 import org.apache.flink.test.util.ForkableFlinkMiniCluster;
 
 import org.junit.Assert;
@@ -64,10 +57,10 @@ public void testExternalProgram() {
 			config.setString(ConfigConstants.JOB_MANAGER_IPC_ADDRESS_KEY, "localhost");
 			config.setInteger(ConfigConstants.JOB_MANAGER_IPC_PORT_KEY, testMiniCluster.getLeaderRPCPort());
 
-			Client client = new Client(config);
+			ClusterClient client = new StandaloneClusterClient(config);
 
 			client.setPrintStatusDuringExecution(false);
-			client.runBlocking(program, 4);
+			client.run(program, 4);
 
 		}
 		catch (Throwable t) {