termination handling

- moved to base cli class to handle centrally and duplicate less code
- now avoids duplication and reiteration of signal handler by reassigning it
- left note on how to do non-graceful in case we add in future
  as I won't remember everything i did here and don't want to 'relearn' it.

lib/ansible/executor/playbook_executor.py

@@ -19,11 +19,7 @@
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
-import getpass
-import locale
 import os
-import signal
-import sys
 
 from ansible.compat.six import string_types
 
@@ -32,8 +28,6 @@ from ansible.executor.task_queue_manager import TaskQueueManager
 from ansible.playbook import Playbook
 from ansible.template import Templar
 
-from ansible.utils.unicode import to_unicode
-
 try:
     from __main__ import display
 except ImportError:
@@ -69,8 +63,6 @@ class PlaybookExecutor:
         may limit the runs to serialized groups, etc.
         '''
 
-        signal.signal(signal.SIGTERM, self._terminate)
-
         result = 0
         entrylist = []
         entry = {}
@@ -207,10 +199,6 @@ class PlaybookExecutor:
 
         return result
 
-    def _terminate(self, signum=None, framenum=None):
-        display.debug("Termination signal detected, shutting down gracefully")
-        raise SystemExit
-
     def _get_serialized_batches(self, play):
         '''
         Returns a list of hosts, subdivided into batches based on