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, projects, 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

ec2 credentials: create, delete, list, show

Change-Id: I82ff84ed433cd9a2da9534bf5f584a2e1a3fe68c
Do lookups for user, project

This required https://review.openstack.org/26323 in keystoneclient

Change-Id: I55bededbc20b5dcf2833c59eb2b6b069703d8a9a
Merge branch '27143-role-fix' into dt-test
Merge branch 'identity-ec2' into dt-test