Add Goal in BaseStrategy + Goal API reads from DB

In this changeset, I changed the Strategy base class to add new
abstract class methods. I also added an abstract strategy class
per Goal type (dummy, server consolidation, thermal optimization).

This changeset also includes an update of the /goals Watcher API
endpoint to now use the new Goal model (DB entries) instead of
reading from the configuration file.

Partially Implements: blueprint get-goal-from-strategy
Change-Id: Iecfed58c72f3f9df4e9d27e50a3a274a1fc0a75f

watcher/api/controllers/v1/collection.py

@@ -44,7 +44,7 @@ class Collection(base.APIBase):
         q_args = ''.join(['%s=%s&' % (key, kwargs[key]) for key in kwargs])
         next_args = '?%(args)slimit=%(limit)d&marker=%(marker)s' % {
             'args': q_args, 'limit': limit,
-            'marker': self.collection[-1].uuid}
+            'marker': getattr(self.collection[-1], "uuid")}
 
         return link.Link.make_link('next', pecan.request.host_url,
                                    resource_url, next_args).href