[FLINK-3077][cli] Add version option(-v, --version) to Cli.

This closes apache#1418

flink-clients/src/main/java/org/apache/flink/client/CliFrontend.java

@@ -1000,11 +1000,20 @@ else if (action.equals("-h") || action.equals("--help")) {
  CliFrontendParser.printHelp();
  return 0;
  }
+ else if (action.equals("-v") || action.equals("--version")) {
+ String version = EnvironmentInformation.getVersion();
+ String commitID = EnvironmentInformation.getRevisionInformation().commitId;
+ System.out.print("Version: " + version);
+ System.out.println(!commitID.equals(EnvironmentInformation.UNKNOWN) ? ", Commit ID: " + commitID : "");
+ return 0;
+ }
  else {
  System.out.printf("\"%s\" is not a valid action.\n", action);
  System.out.println();
  System.out.println("Valid actions are \"run\", \"list\", \"info\", or \"cancel\".");
  System.out.println();
+ System.out.println("Specify the version option (-v or --version) to print Flink version.");
+ System.out.println();
  System.out.println("Specify the help option (-h or --help) to get help on the command.");
  return 1;
  }