Remove acl9, replace with SimpleRole

acl9 gem is a little bit opaque, had (at least one) rails 4.1.x incompatibility, and its tests are written in a convluted style with Test::Unit. Since our needs are simple (see what I did there?), rewrite, as SimpleRole, only implementing the methods that we use, and hardcoding (would be simple to generalize, but there is no need) class names for associations.
Rename `has_role!` to `grant_role!`

Also, add tests, remove `has_role_for?(...)`, since it isn't used.
Remove owner association

Since we have roles now, just use that to show ownership of applications
add `revoke_role(...)`
Merge branch 'devel' into feature/simple_role

Conflicts:
	app/controllers/api/v1/tasks_controller.rb
Give application owners correct role on resource
Merge pull request #423 from 18F/feature/simple_role

Remove acl9, replace with SimpleRole