This updates the alarm API to match the latest discussion:
https://wiki.openstack.org/wiki/Ceilometer/blueprints/alarm-api
It allows creation of different kinds of alarm.
The current kind of alarm has been named 'threshold'.
It move the defaults values from the storage models to the API
with all tools provided by wsme to ensure mandatory field and default.
A behavior change, it is now mandatory to PUT a full alarm description
in a PUT call.
In the future a new endpoint can be added to allow to modify only one
field (example for state: /v2/alarms/<id>/state)
Implements blueprint alarming-logical-combination
Change-Id: Ib85636728d427cdb70ef530ff9ff20d2b75c5ed1
48c85f740a