attempt to replace homegrown authorization with pundit
Policies are once again Authorizers
Reintroduce Supermarket::Authorization as a layer on top of Pundit
Remove CanCan-style helpers

Pundit provides an approximation that is a little more direct:

    policy(resource).create? # Can the current user create resource
Remove Supermarket authorization helper method injection
ApplicationController should use Supermarket::Authorization
Supermarket::Authentication handles authentication requirements
override pundity policy_class by default of ActiveRecord::Base objects
adjust location store functionality so invitations work after rebase