Code refactoring - Watcher Decision Engine package

This patchset is there to change the code structure.
The objective is to flatten the project file tree by merging
'api/' and 'framework/' into a single package. This also contains
some tidy ups in package naming (like using only singular nouns).

This should only affect file/folder names and their subsequent
import paths wherever they were used.

Change-Id: Ie903ba20ca5cf03b0b42efa60131d1b919b0c2c9

watcher/common/messaging/events/event_dispatcher.py

@@ -16,7 +16,7 @@
 
 from oslo_log import log
 
-from watcher.decision_engine.framework.messaging.events import Events
+from watcher.decision_engine.messaging.events import Events
 
 LOG = log.getLogger(__name__)