pass default_config_dirs variable for config initialization.

Currently default config files are being for initialization of CONF from
oslo_config. However default config dirs are not being passed as a
result watcher components (eg: decision-engine) are unable to load
files from default directories (eg: /etc/watcher/watcher.conf.d)
supported by oslo_config. This is a short-coming on watcher's side.
Also this forces user to have multiple config for each component.

Without this default set, oslo_config will search for conf with string
'python-watcher' in it, eg: /etc/python-watcher/.... Since there is a
because project=python-watcher a couple of lines below

This patch adds the option after evaluating using project as 'watcher'
which is similar to evaluation of default_config_files and also allows
it to be passed in as a function parameter.

Change-Id: I013f9d03978f8716847f8d1ee6888629faf5779b
(cherry picked from commit dce23d7eb4)

watcher/common/config.py

@@ -21,12 +21,15 @@ from watcher.common import rpc
 from watcher import version
 
 
-def parse_args(argv, default_config_files=None):
+def parse_args(argv, default_config_files=None, default_config_dirs=None):
     default_config_files = (default_config_files or
                             cfg.find_config_files(project='watcher'))
+    default_config_dirs = (default_config_dirs or
+                           cfg.find_config_dirs(project='watcher'))
     rpc.set_defaults(control_exchange='watcher')
     cfg.CONF(argv[1:],
              project='python-watcher',
              version=version.version_info.release_string(),
+             default_config_dirs=default_config_dirs,
              default_config_files=default_config_files)
     rpc.init(cfg.CONF)