Fix race condition in CampaignView

Sometimes, the poll request will return 404, and when that happens
the view stops listening to the supermodel and it never really 'loads',
and looks as if the user did not have any sessions. Changed the
'stop listening' behavior to only happen for blocking requests, ie
ones with value greater than 0.

app/views/core/CocoView.coffee

@@ -229,7 +229,8 @@ module.exports = class CocoView extends Backbone.View
   # Error handling for loading
   onResourceLoadFailed: (e) ->
     r = e.resource
-    @stopListening @supermodel
+    if r.value
+      @stopListening @supermodel
     return if r.jqxhr?.status is 402 # payment-required failures are handled separately
     @showError(r.jqxhr)
 

app/views/play/CampaignView.coffee

@@ -152,7 +152,7 @@ module.exports = class CampaignView extends RootView
       @supermodel.addRequestResource(url: '/picoctf/problems', success: (@picoCTFProblems) =>).load()
     else
       unless @editorMode
-        @sessions = @supermodel.loadCollection(new LevelSessionsCollection(), 'your_sessions', {cache: false}, 0).model
+        @sessions = @supermodel.loadCollection(new LevelSessionsCollection(), 'your_sessions', {cache: false}, 1).model
         @listenToOnce @sessions, 'sync', @onSessionsLoaded
       unless @terrain
         @campaigns = @supermodel.loadCollection(new CampaignsCollection(), 'campaigns', null, 1).model