Move from using _ builtin to using glance.i18n _

The builtin _ should not longer be used.  Instead _
should be explicitly assigned from glance.i18n.

This patch does the following:
  (1) adds these explict assignments to any
      glance file that was missing them,
  (2) removes the defintion of _ as a builtin from
      tox.ini so that a pep8 failure will occur
      if _ is not defined,
  (3) removes calls to install().

This removes the last direct use of gettextutils by glance.
The indirect uses, via openstack/common, will be removed
in the next sync with oslo.

Change-Id: Ie54e8a67e747e022cc01022dfad35d89686bdfc4
Merge "Move from using _ builtin to using glance.i18n _"