add unit tests for GIT* definitions

This adds unit tests for all the GIT* definitions, ensuring that for
libraries we think should be defined, they are. It exposed a bug in
glance_store definitions in the process.

The GITDIR definition for python-openstackclient is moved to stackrc
for testability.

Change-Id: Ibd9ab665f0362a84f4f7e80e80da56a4737f584e
Merge "add unit tests for GIT* definitions"