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.

note, b/c there's some funny business with application ownership, DO NOT MERGE until we update the data.
- mixin is just naming
- extend sucks all the module methods in as class methods
- include sucks all the module methods in as instance methods (and you can create a special method as `def self.included(base) ... ` that runs when the module is included

so ... what's going on here is that acts_as_auth...* methods are all class methods on `ActiveRecord::Base` and `acts_as_authorization_subject` includes a couple more methods in the class from which it is called. Namely, `User` gets the `grant_role!` and `has_role?` methods.