Switch from signing/format --> token/provider.

Keystone Havana has now deprecated the old signing format config
file format. It now uses token/provider instead.

token_format is now deprecated.

Closes-Bug #1223265

Change-Id: Ia7c089b51823ad2a559a435b08dfca7364de2979
Merge "Switch from signing/format --> token/provider."
Merge git://github.com/puppetlabs/puppetlabs-keystone