done!
add a custom #inspect method to most classes

* most of these classes have an instance variable containing a
  Raca::Account, which can lead to pages and pages of console output if
  you call inspect
* Let's implement custom inspect methods that only contain the key
  details (username, region, container name, etc) for each instance
Merge pull request #8 from conversation/better-inspect

add a custom #inspect method to most classes
Raca::Account#public_endpoint should handle 'identity' as a special case

* the identity API isn't included in the service catalog, it's the one
  API endpoint that is hard coded
* Until now it was only used in the Account class, but we're about to
  start using it for user management
Add basic support for listing users on the rackspace account

* To begin with, it's only possible to view the basic user details, but
  this is the foundation for more complex functionality
only store a single copy of the identity URL