Rename translation fixtures, explicitly use problem ids

test/fixtures/translations.yml

@@ -1,11 +1,11 @@
 # Read about fixtures at http://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
 
-one:
-  problem: one
+translation_one:
+  problem_id: 1
   title: First title
   content: The content of the translation
 
-two:
-  problem: two
+translation_two:
+  problem_id: 2
   title: Second title
   content: The content of the second translation