Sync with oslo-incubator 28fba9c

This syncs Keystone with oslo-incubator commit hash
28fba9c262943e3f6b0b10321680fc08cf6b8387 .

In keystone:

$ rm -r keystone/openstack/common

In oslo-incubator:

$ python update.py ../keystone

Commits
-------
0f495ee Emit a log statement when releasing internal lock
9912e5d Add API for creating translation functions

Change-Id: If8c8f6aa96408d7d15e17a0e70e18d7d25df2285
Merge "Sync with oslo-incubator 28fba9c"