Identity API: Add Role parameters are incorrectly specified

[Sam Harwell]

The Identity Service Add Role operation is not properly described.

http://docs.openstack.org/api/openstack-identity-service/2.0/content/POST_addRole_v2.0_OS-KSADM_roles_Role_Operations_OS-KSADM.html

1. The `name` parameter is listed as part of the query string and as part of the request body. Which one is correct?

2. The `id` value in the body is not properly described. In most instances, the `id` for an entity is created by the server, but it appears to be created by the client in this example. The documentation should be updated to clearly state the intentions and requirements for clients since this example substantially deviates from other example calls.

[Diane Fleming (diane-fleming)]

backport: havana