Implement track requests and add the track organizer role

About track requests:
Create migration that adds the fields submitter_id, state, and
cfp_active to Tracks
Add validations and the self_organized? method to the Track model
Create a new TracksController outide of the admin namespace
Create the relevant views for index, show, new and edit
Modify the admin views for tracks to include extra info for
self-organized tracks

About track organizers:
Create the role when a self-organized track is created
Define track organizer abilities
Modify the roles views and controller to handle the new role

The route for Roles#edit needs to have higher priority than the nested
routes for track roles, otherwise, the word edit in the url is matched
as a track with short_name edit

spec/factories/tracks.rb

@@ -5,5 +5,11 @@ FactoryGirl.define do
     color { Faker::Color.hex_color }
     short_name { SecureRandom.urlsafe_base64(5) }
     program
+
+    trait :self_organized do
+      association :submitter, factory: :user
+      state 'new'
+      cfp_active false
+    end
   end
 end