remove default=None for config options

In the cfg module default=None is set as the default value.

Change-Id: I65786401354e5fb966339cbdb4a76f5f628b8d6f
Closes-Bug: #1323975

ceilometer/cli.py

@@ -135,8 +135,7 @@ def send_sample():
                    required=True),
         cfg.StrOpt('sample-unit',
                    short='U',
-                   help='Meter unit.',
-                   default=None),
+                   help='Meter unit.'),
         cfg.IntOpt('sample-volume',
                    short='l',
                    help='Meter volume value.',

ceilometer/dispatcher/file.py

@@ -24,7 +24,6 @@ from ceilometer import dispatcher
 
 file_dispatcher_opts = [
     cfg.StrOpt('file_path',
-               default=None,
                help='Name and the location of the file to record '
                     'meters.'),
     cfg.IntOpt('max_bytes',

ceilometer/storage/__init__.py

@@ -35,7 +35,6 @@ STORAGE_ENGINE_NAMESPACE = 'ceilometer.storage'
 OLD_STORAGE_OPTS = [
     cfg.StrOpt('database_connection',
                secret=True,
-               default=None,
                help='DEPRECATED - Database connection string.',
                ),
 ]