Track related fixes

Make the message in admin/Tracks form more visible by making it bold and
adding links to venue and rooms
Make papertrail track changes for all the track's attributes
Add validation to require presence of description for self-organized
tracks
Add ID column to admin/Tracks#index
Make the cfp inclusion column sortable
Show success/error flash messages after toggling cfp inclusion

app/controllers/admin/tracks_controller.rb

@@ -4,6 +4,9 @@ module Admin
     load_and_authorize_resource :program, through: :conference, singleton: true
     load_and_authorize_resource through: :program, find_by: :short_name
 
+    # Show flash message with ajax calls
+    after_action :prepare_unobtrusive_flash, only: :toggle_cfp_inclusion
+
     def index; end
 
     def show
@@ -55,9 +58,13 @@ module Admin
     def toggle_cfp_inclusion
       @track.cfp_active = !@track.cfp_active
       if @track.save
-        head :ok
+        flash[:notice] = "Successfully changed cfp inclusion of #{@track.name} to #{@track.cfp_active}"
       else
-        head :unprocessable_entity
+        flash[:error] = "Failed to toggle cfp inclusion of #{@track.name} to #{@track.cfp_active}"
+      end
+
+      respond_to do |format|
+        format.js
       end
     end