explore new API options in the README
move fixtured identity API response into spec/
add ir_b as a development dependency
significantly simplify the Raca::Account API

* It isn't responsible for parsing the identity API response and
  splitting endpoint URLs into components
* It just manages the identity request, caches the response and provides
  a convenience method for fetching the specific API endpoint for a
  service in a region
* This should mean new services, regions and endpoints will be supported
  with no code changes
remove unused code
scope account caching to usernames

* so Accounts for multiple rackspace users don't share data
setup Bucket to be instantiated via an Account instance

* Instead of making the user create a new Bucket instance directly, we
  want them to do something like:

    account = Raca::Account.new("username", "api_key")
    container = account.containers(:ord).get("foobar")
    puts container.metadata

* This means Bucket is no longer hard coded to use the ORD region, users
  can access any rackspace region
Setup Raca::Server to be instantiated via Raca::Account
rename Raca::Bucket to Raca::Container

* this library is specific to rackspace cloud, so we should be
  consistent with their terminology