Add debates translation interface

Also fix broken spec after removing translatable attributes from
strong_parameters definition. Now we need to send these attributes
as nested translations attributes.

Use activerecord.yml title attribute label so form helper could load it
from default location.

spec/controllers/debates_controller_spec.rb

@@ -12,16 +12,19 @@ describe DebatesController do
     end
 
     it "creates an ahoy event" do
-
+      debate_attributes = {
+        terms_of_service: "1",
+        translations_attributes: {
+          "0" => {
+            title: "A sample debate",
+            description: "this is a sample debate",
+            locale: "en"
+          }
+        }
+      }
       sign_in create(:user)
 
-      post :create, params: {
-                      debate: {
-                        title: "A sample debate",
-                        description: "this is a sample debate",
-                        terms_of_service: 1
-                      }
-                    }
+      post :create, debate: debate_attributes
       expect(Ahoy::Event.where(name: :debate_created).count).to eq 1
       expect(Ahoy::Event.last.properties["debate_id"]).to eq Debate.last.id
     end