Replace the incubated copy of gettextutils with oslo.i18n, following the
best-practices guidelines in the library documentation for handling
imports, module names, and exceptions to the hacking rules.
Change-Id: Ie366afd8bda2a72c964d9ddf7dd53718002fb4d0
Story: 2000776
Signed-off-by: Doug Hellmann <doug@doughellmann.com>