Return 400 for invalid filter combinations on /role_assignments API

[Samuel de Medeiros Queiroz]

On /v3/role_assignments API, there are two types of invalid filter combinations:

1) Can't combine actors or targets:
- (domain_id, project_id)
- (user_id, group_id)

2) Can't filter results by something that is never returned in effective mode:
- (effective, group)
- (effecitve, inherited, domain)

We need to raise an exception, returning 400 status code when those parameters are provided.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/144703

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/144703
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=569a42b3a140b0310e7d28ceb5ea8281febc4096
Submitter: Jenkins
Branch: master

commit 569a42b3a140b0310e7d28ceb5ea8281febc4096
Author: Samuel de Medeiros Queiroz <email address hidden>
Date: Thu Jan 1 14:30:32 2015 -0300

    Check for invalid filtering on v3/role_assignments

    HTTP 400 is returned for invalid filters:
    - domain and project
    - user and group
    - effective and group
    - effective, domain and inherited

    Closes-Bug: 1406667

    Change-Id: Iac64856424a80935d34631e2243da4fc329ab2a0