kill unused (i hope) participations collection

app/assets/javascripts/app/collections/participations.js

@@ -1,7 +0,0 @@
-app.collections.Participations = Backbone.Collection.extend({
-  model: app.models.Participation,
-
-  initialize : function(models, options) {
-    this.url = "/posts/" + options.post.id + "/participations" //not delegating to post.url() because when it is in a stream collection it delegates to that url
-  }
-});