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/tests/db/test_goal.py

@@ -242,17 +242,15 @@ class DbGoalTestCase(base.DbTestCase):
         self.assertEqual(uuids.sort(), res_uuids.sort())
 
     def test_get_goal_list_with_filters(self):
-        goal1_uuid = w_utils.generate_uuid()
-        goal2_uuid = w_utils.generate_uuid()
         goal1 = self._create_test_goal(
             id=1,
-            uuid=goal1_uuid,
+            uuid=w_utils.generate_uuid(),
             name="GOAL_1",
             display_name='Goal 1',
         )
         goal2 = self._create_test_goal(
             id=2,
-            uuid=goal2_uuid,
+            uuid=w_utils.generate_uuid(),
             name="GOAL_2",
             display_name='Goal 2',
         )