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

app/controllers/tracks_controller.rb

@@ -0,0 +1,47 @@
+class TracksController < ApplicationController
+  load_resource :conference, find_by: :short_title
+  load_resource :program, through: :conference, singleton: true
+  load_and_authorize_resource through: :program, find_by: :short_name
+
+  def index
+    @tracks = current_user.tracks.where(program: @program)
+  end
+
+  def show; end
+
+  def new
+    @track = @program.tracks.new(color: @conference.next_color_for_collection(:tracks))
+  end
+
+  def edit; end
+
+  def create
+    @track = @program.tracks.new(track_params)
+    @track.submitter = current_user
+    @track.state = 'new'
+    @track.cfp_active = false
+    if @track.save
+      redirect_to conference_program_tracks_path(conference_id: @conference.short_title),
+                  notice: 'Track request successfully created.'
+    else
+      flash.now[:error] = "Creating Track request failed: #{@track.errors.full_messages.join('. ')}."
+      render :new
+    end
+  end
+
+  def update
+    if @track.update_attributes(track_params)
+      redirect_to admin_conference_program_tracks_path(conference_id: @conference.short_title),
+                  notice: 'Track request successfully updated.'
+    else
+      flash.now[:error] = "Track request update failed: #{@track.errors.full_messages.join('. ')}."
+      render :edit
+    end
+  end
+
+  private
+
+  def track_params
+    params.require(:track).permit(:name, :description, :color, :short_name)
+  end
+end