Remove redundant "participation not allowed" code

Very similar code is present in the `votes.js` file. Since the only
elements with the `js-participation-not-allowed` class also matched the
`div.supports div.participation-not-allowed` selector, for these
elements the events were executed twice.

So we can get rid of the `js-participation` class alongside all the
JavaScript code referencing it.

app/assets/javascripts/application.js

@@ -66,7 +66,6 @@
 //= require tags
 //= require users
 //= require votes
-//= require allow_participation
 //= require advanced_search
 //= require registration_form
 //= require suggest
@@ -124,7 +123,6 @@ var initialize_modules = function() {
   App.Comments.initialize();
   App.Users.initialize();
   App.Votes.initialize();
-  App.AllowParticipation.initialize();
   App.Tags.initialize();
   App.FoundationExtras.initialize();
   App.LocationChanger.initialize();