Horizon needs a version of troveclient < 1

We should not build off the tag > 1 as horizon for havana needs a
version < 1.  They are currently working on fixing this, and may
backport the fix to havana.

Versioning pinning:
https://bugs.launchpad.net/horizon/+bug/1238121

Attempt to get new version:
https://bugs.launchpad.net/horizon/+bug/1250237
https://review.openstack.org/#/c/56483/

Change-Id: I4c7de5e839ee7a8f22ea39b15d3fc153fc820452
Merge "Horizon needs a version of troveclient < 1"