updates to tenant used for quantum user

This commit makes two small updates to the internal user that
quantum uses for authentication.

1. makes this user's tenant configurable (in quantum::keystone::auth)
2. set the default tenant in l3 to be services (instead of service for consistency with other modules)
update metadata_ip default

metadata_ip is the address where the metadata service
should be routed to.

This commit changes the default from 169.254.169.254 to
localhost.
only configure ports and bridges with bridge mappings

this commits adds code so that ports and bridges are
only configured when bridge mappings are specified.
add region to title for keystone auth

to make quantum compatible with the latest vesrsion of
the keystone module.