Add auth_admin_prefix support for ceilometer::api

To support keystone urls like http://host:80/keystone/admin

Implements blueprint serve-keystone-from-wsgi

Change-Id: I68c17a5b76ed61b18337ee580fba63200d874792
Switch deprecated rabbit_notifier to rpc_notifier

The 'nova.openstack.common.notifier.rabbit_notifier' is deprecated since
the G release of Openstack, it has to be replaced with
'nova.openstack.common.notifier.rpc_notifier'.

Change-Id: I2174bc1b6504bacfeb427b2f5b8f8dc19c167dcb
Merge "Add auth_admin_prefix support for ceilometer::api"
Replace deprecated :rubygems source

Fix deprecation warnings thrown by bundler:

  The source :rubygems is deprecated because HTTP requests are insecure.
  Please change your source to 'https://rubygems.org' if possible,
  or 'http://rubygems.org' if not.

Change-Id: Ifaba2b94d7b47cd32b9bb6eec04cf7f4b89d0411
Remove duplicated fixtures

Sort fixtures for better maintainability.

Change-Id: I17d4229584e2df2da2666e00f17bfcacdb8cdd03