Using a mutable type implies that it's acceptable for the set of
publicly-accessible attributes to be mutated at runtime, which defeats
their intended purpose of documenting the public interface. Tuples are
immutable.

Change-Id: Ib3ab93224ba240040b08ece481ef5ba620c3f658

Define which interfaces are public and which are internal based
on PEP 8.

For reference, PEP 8 section is here:
http://www.python.org/dev/peps/pep-0008/#public-and-internal-interfaces

Change-Id: I14233796b7838b78fbd355014478f3e326542966

- 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