Add Voluptuous to validate the action parameters

We want a simplest way to validate the input parameters of an
Action through a schema.

APIImpact
DocImpact
Partially implements: blueprint watcher-add-actions-via-conf

Change-Id: I139775f467fe7778c7354b0cfacf796fc27ffcb2

watcher/api/controllers/v1/action.py

@@ -129,13 +129,10 @@ class Action(base.APIBase):
     alarm = types.uuid
     """An alarm UUID related to this action"""
 
-    applies_to = wtypes.text
-    """Applies to"""
-
     action_type = wtypes.text
     """Action type"""
 
-    input_parameters = wtypes.DictType(wtypes.text, wtypes.text)
+    input_parameters = types.jsontype
     """One or more key/value pairs """
 
     next_uuid = wsme.wsproperty(types.uuid, _get_next_uuid,