Adding query filtering support to Sahara

In order to better handle potentially large result
sets, Sahara needs to support filtering via query
parameters.  This spec lays out the affected areas
(sahara service, python-saharaclient, horizon).
APIImpact

Change-Id: Id735e1ffd0f966f93c1f6a27fd1378d02385256c
Merge "Adding query filtering support to Sahara"