Parameterize the swift-ring role

Previously I had hard-coded the values for the swift ring creation.
Obviously, these are better off being parameterized.
Update rebalance to guard against reblancing

Require that reblance must be forced if a ring change would change an
existing ring.
Add a swift-dispersion check

This dispersion check will give us a good baseline for general cluster
health. Also adding all of the necessary sensu infrastructure to
support swift checks.
Make sure we have keystone client

We need keystone client for swift auth, so make sure have the client
prior to swift being installed.
Add a missing curly

This template was checked in with a missing curly bracket. Oops.
Merge pull request #267 from craigtracey/swifttweak

Some Swift Tweaks