Propose a suite of declarative http api tests
Propose a suite of declarative http api tests

To improve testing of the various aspects of the HTTP API, both in
terms of coverage and readability, a suite of readable declarative
tests is proposed.

Change-Id: Id7a62f81368794624a89a6c33efd37c6a529548f

openstack/ceilometer-specs,openstack/telemetry-specs