Remove gettext.install() from glance/__init__.py

The gettext.install() function installs a builtin _() function which
translates a string in the translation domain supplied to the install()
function. If gettext.install() is called multiple times, it's the last
call to the function which wins and the last supplied translation domain
which is used e.g.

 >>> import os
 >>> os.environ['LANG'] = 'ja.UTF-8'
 >>> import gettext
 >>> gettext.install('keystone', unicode=1, localedir='/opt/stack/keystone/keystone/locale')
 >>> print _('Invalid syslog facility')
 無効な syslog ファシリティ
 >>> gettext.install('nova', unicode=1, localedir='/opt/stack/nova/nova/locale')
 >>> print _('Invalid syslog facility')
 Invalid syslog facility

Usually this function is called early on in a toplevel script and we
assume that no other code will call it and override the installed _().
However, in Glance, we have taken a shortcut to avoid having to call it
explicitly from each script and instead call it from glance/__init__.py.

This shortcut would be perfectly fine if we were absolutely sure that
glance modules would never be imported from another program. It's probably
quite incorrect for a program to use glance code (indeed, if we wanted to
support this, Glance code shouldn't use the default _() function) but
nevertheless there are some corner cases where it happens. For example,
the keystoneclient auth_token middleware tries to import cfg from
gance.openstack.common and this in turn causes gettext.install('glance')
to be called in other projects like glance or quantum.

To avoid any doubt here, let's just rip out the shortcut and always
call gettext.install() from the top-level script.

However, there's a bit of an annoying detail here - by default,
nosetests starts in the current directly and tries to import all modules
it finds to look for tests. Without the _() builtin installed, importing
some modules like glance.common.exception will fail.

Since it only ever makes sense to load tests from the glance/tests dir,
we can ask nose to do that by using the --tests argument via setup.cfg.

Note, this means that if you previously did this:

  $> tox -- glance.tests.foo glance.tests.bar

then you must now do this:

  $> tox -- --tests glance.tests.foo,glance.tests.bar

Change-Id: If4125d6bcbde63df95de129ac5c83b4a6d6f130a
Small change to 'is_public' documentation

Update the documentation for 'is_public' in authentication.rst
to be more accurate.

Addresses bug 1177732.

Change-Id: I9889826d4019ff33d9be343e79324862d9fde8e9
Merge "Small change to 'is_public' documentation"
Merge "Remove gettext.install() from glance/__init__.py"