update README

Change-Id: Id122f1e148e975b48516ae802d1447bcffcafa3a
Add glance::db::postgresql class.

This allows Glance to be used with PostgreSQL.

Requires the puppetlabs/postgresql module. NOTE: I did add this
dependency to fixtures but did not add it to the Modulefile due
to the fact that the postgresql::python module hasn't been
released to puppetforge yet (although it is committed and tests
pass).

Change-Id: I3522d50935c81c8859c9f597df64aa0af6ca4e71
Allow paste deploy flavor to be passed for glance api

Some users may want to pass in one of
keystone, keystone+caching or keystone+cachemanagement
depending on their caching needs

Change-Id: Ia13cc2f1d8ec43074b114edf1b2366b85ca77aa0
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.

Fixes: bug #1175767
Change-Id: Id577d1d4c057827ce0d53c9bbedc66a8d290f54b
Merge branch 'dev' of https://github.com/gwdg/puppetlabs-glance into dev