pass default_config_dirs variable for config initialization.
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

openstack/watcher,stackforge/watcher,stackforge/watcher,openstack/watcher