fix instruments part of payload

app/views/api_users/show.rabl

@@ -15,7 +15,7 @@ unless @user.bands.nil? || @user.bands.size == 0
 end
 
 unless @user.instruments.nil? || @user.instruments.size == 0
-  child :instruments => :instruments do
-    attributes :id, :description, :proficiency_level
+  child :user_instruments => :instruments do
+    attributes :description, :proficiency_level
   end
 end