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/api/controllers/v1/audit.py

@@ -30,7 +30,7 @@ from watcher.api.controllers.v1 import types
 from watcher.api.controllers.v1 import utils as api_utils
 from watcher.common import exception
 from watcher.common import utils
-from watcher.decision_engine.framework.rpcapi import DecisionEngineAPI
+from watcher.decision_engine.rpcapi import DecisionEngineAPI
 from watcher import objects