capping python-troveclient version

Verson 1.0 of python-troveclient is not backwards compatible with
the trove work in Horizon. There are too many places to fix the
compatibility issues for Havana, so for now pinning the release
version.

Closes-bug: #1238121

Change-Id: If0ec929180e083aa47bdb688879ba2f63fdcd2a3
(cherry picked from commit b49b952be096c4d50228b5ca0dc40ad19e0211a6)