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

db/migrate/20170705075039_add_state_cfp_active_and_submitter_reference_to_tracks.rb

@@ -0,0 +1,8 @@
+class AddStateCfpActiveAndSubmitterReferenceToTracks < ActiveRecord::Migration
+  def change
+    add_column :tracks, :state, :string
+    add_column :tracks, :cfp_active, :boolean
+    add_column :tracks, :submitter_id, :integer
+    add_index :tracks, :submitter_id
+  end
+end

db/schema.rb

@@ -483,16 +483,21 @@ ActiveRecord::Schema.define(version: 20170711102511) do
   end
 
   create_table "tracks", force: :cascade do |t|
-    t.string   "guid",        null: false
-    t.string   "name",        null: false
+    t.string   "guid",         null: false
+    t.string   "name",         null: false
     t.text     "description"
     t.string   "color"
     t.datetime "created_at"
     t.datetime "updated_at"
     t.integer  "program_id"
-    t.string   "short_name",  null: false
+    t.string   "short_name",   null: false
+    t.string   "state"
+    t.boolean  "cfp_active"
+    t.integer  "submitter_id"
   end
 
+  add_index "tracks", ["submitter_id"], name: "index_tracks_on_submitter_id"
+
   create_table "users", force: :cascade do |t|
     t.string   "email",                  default: "",    null: false
     t.string   "encrypted_password",     default: "",    null: false