Add strategy_id & goal_id fields in audit template

In this changeset, I updated the 'goal_id' field into the AuditTemplate
to now become a mandatory foreign key towards the Goal model. I also
added the 'strategy_id' field into the AuditTemplate model to be an
optional foreign key onto the Strategy model.

This changeset also includes an update of the /audit_template
Watcher API endpoint to reflect the previous changes.

As this changeset changes the API, this should be merged alongside the
related changeset from python-watcherclient.

Partially Implements: blueprint get-goal-from-strategy

Change-Id: Ic0573d036d1bbd7820f8eb963e47912d6b3ed1a9

watcher_tempest_plugin/tests/api/admin/test_action.py

@@ -30,7 +30,8 @@ class TestShowListAction(base.BaseInfraOptimTest):
     @classmethod
     def resource_setup(cls):
         super(TestShowListAction, cls).resource_setup()
-        _, cls.audit_template = cls.create_audit_template()
+        _, cls.goal = cls.client.show_goal("DUMMY")
+        _, cls.audit_template = cls.create_audit_template(cls.goal['uuid'])
         _, cls.audit = cls.create_audit(cls.audit_template['uuid'])
 
         assert test.call_until_true(