Support unicode via en_US.utf8

Because C.utf8 is not everywhere and is sometimes called C.UTF-8 (just
to confuse people) use en_US.utf8 which is in most places. This isn't
language/region agnostic but gives a consistent unicode aware locale to
devstack.

Change-Id: I67a8c77a5041e9cee740adf0e02fdc9b183c5bc4
fixes-bug: 1697733
1 file changed