Remove duplicate apis for list users/projects in a domain

The form:

GET /domains/{domain_id}/users
GET /domains/{domain_id}/projects

can be achieved in the same way by using the query filter on

GET /users
GET /projects

e.g.:

GET /users?domain_id="my domain"

Fixes Bug #1126048

Change-Id: I2d4e03d46fc9bd6b3d268f656f2eb83e81c1f5c5