In many places we were checking for identity which was the shorthand for
checking if the resource had been saved by the service.
The #persisted? method was added to show a clearer intent and also offer
minimal ActiveModel interface
Added ability to set "metadata" and "personality" fields when creating a server on Rackspace Compute v2.
Improved response parsing when dealing with Rackspace DNS service.
Provides a method for determining next-gen server passwords.
Adds a read-only attribute to next-gen servers for storing
the root password. The attribute is set whenever a new server
is created or the password on an existing server is changed.
