Finish up v3 role commands

* Add remove role
* Add --role to group list
* Add --role to user list
* Fix groups in AddRole()
* Remove the tweaks to utils.find_resource for domains; will address
  that across domains, users and groups in another patch.
  I want to nail down the structure of these commands and get that into place

Change-Id: I8673dd8221ef88978dada5a2833c187026bdb31a
Add EC2 credentials CRUD

Change-Id: I6e2b14ebe9f1af0d083f793c9833a7b255ac3531
Merge branch '27143-role-fix' into dt-test
Merge branch 'compute-ec2' into dt-test