temporarily cap python-troveclient version

Version 1.0 from the HttpClient perspective is not backward
compatible.  Horizon has trove integration in Havana and
significant rework would be required to fix the compatibility
issues for the Havana release.

This cap would only be for the Havana release.

Partial-bug: #1238121

Change-Id: I52e8ddc4a8f79ec7f358a07d00aabe9c2046b6c7