This BP propose to support users can query resources by specifying the time
comparison operators along with created_at or updated_at fields,
and cinder will return all which match the condition.
Will add six time comparison operators in querying API.
"volumes/detail?updated_at=gt:2016-01-01T01:00:00,lt:2016-12-01T01:00:00"
Change-Id: Ia041bf4e1205cdb9c3b94af6566e4850fb54eecc