Part of fixing bug #995287
Syncs these two commits from oslo-incubator:
Support overriding oslo localedir too
Add a gettextutils.install() helper function
to get a new gettextutils.install() function which allows the default
localedir to be overwritten via an environment variable.
Note that gettextutils.install() must be called before any other cinder
modules are imported since some modules attempt to translate strings
at import time (e.g. in cinder.flags). This is broken and inefficient,
but fixing it involves adding something like sphinx's l_() function and
would be very invaisve.
Change-Id: I86562b3a65d371673bb21f7179eecc7602bc0775
68f28d257c