Namespace updates for _i18n and imageutils & fileutils

Namespace updates for _i18n and imageutils & fileutils

The _i18n and imageutils modules only have changes
to move oslo.utils to the oslo_utils namespace and
oslo.i18n to oslo_i18n.  So, I have lumped these
two small changes into this one patch.

Current HEAD in OSLO:
---------------------
commit e589dde0721a0a67e4030813e582afec6e70d042
Date:  Wed Feb 18 03:08:12 2015 +0000
Merge "Have a little fun with release notes"

Changes merged with this patch:
---------------------
_i18n.py
  0cc741a9 - switch to oslo_i18n
imageutils.py
  ac17de97 - Use oslo_utils instead of deprecated oslo.utils
fileutils.py
  ac17de97 - Use oslo_utils instead of deprecated oslo.utils

Change-Id: I749dd8869bbc07d980300e0acbf3903ff7b297cd