2012.1 "Essex"

Merge "Endpoints: Add create, delete, list support"

Support for version and extension discovery

- Supports unauthenticated call to Keystone to discover
  supported API versions
- Added command-line support (usage: keystone discover)
- Added client support (keystoneclient.genenric client).
  Client returns dicts, whereas shell command prints
  formated output.
- Added tests for genenric client
- Replicates 'nove discover' in python-novaclient
- Starts to address blueprint keystone-client
- keystone discover output looks like this:
    $ keystone discover
    Keystone found at http://localhost:35357
        - supports version v1.0 (DEPRECATED) here http://localhost:35357/v1.0
        - supports version v1.1 (CURRENT) here http://localhost:35357/v1.1
        - supports version v2.0 (BETA) here http://localhost:35357/v2.0
            - and HP-IDM: HP Token Validation Extension
            - and OS-KSADM: Openstack Keystone Admin
            - and OS-KSCATALOG: Openstack Keystone Catalog

Change-Id: Id16d34dac094c780d36afb3e31c98c318b6071ac