Fix default avatars to ensure that helpers don't have /assets dir appended

app/helpers/application_helper.rb

@@ -82,7 +82,7 @@ module ApplicationHelper
   end
   def default_avatar
-    image_path('no_avatar.png')
+    'no_avatar.png'
   end
   def last_commit(project)

app/helpers/groups_helper.rb

@@ -27,7 +27,7 @@ module GroupsHelper
     if group && group.avatar.present?
       group.avatar.url
     else
-      image_path('no_group_avatar.png')
+      'no_group_avatar.png'
     end
   end