Add volume migrate action

This patch adds volume migrate action.

Change-Id: I9f46931d2a7edff4c727d674ec315924b9ae30c2
Implements: blueprint volume-migrate-action

watcher/decision_engine/planner/weight.py

@@ -47,7 +47,8 @@ class WeightPlanner(base.BasePlanner):
         super(WeightPlanner, self).__init__(config)
 
     action_weights = {
-        'nop': 60,
+        'nop': 70,
+        'volume_migrate': 60,
         'change_nova_service_state': 50,
         'sleep': 40,
         'migrate': 30,
@@ -64,6 +65,7 @@ class WeightPlanner(base.BasePlanner):
         'change_nova_service_state': 1,
         'nop': 1,
         'change_node_power_state': 2,
+        'volume_migrate': 2
     }
 
     @classmethod