incorrect project name for osloc_config

Looks like watcher is providing the wrong project name to oslo_config, which causing it to search to wrong place for config files.

https://github.com/openstack/watcher/blob/master/watcher/common/config.py#L31

It should've been "watcher" instead of "python-watcher". Otherwise, osloc_config will search "/etc/python-watcher/" instead of "/etc/watcher/" for config files.