Add User roles with AR Enum assoc. with Pundit gem
Merge branch 'sti_on_users' of https://github.com/CelineMartinetSanchez/baobab into artwork

Conflicts:
	baobab/Gemfile.lock
	baobab/app/controllers/application_controller.rb
	baobab/app/views/layouts/application.html.erb
	baobab/db/schema.rb