Show/hide reference warnings on delete and add/rename questions

http://manage.dimagi.com/default.asp?137480

Other minor changes in this PR:
- 6ab1b21 make tests run faster. YES!
- 3839323 @emord reported that his dev/test setup was using the built version when running stand-alone. This turned out to be because his test page URL did not contain the string "localhost". The logic for detecting when to use the built version could be simplified since we are not using heroku for testing anymore.
That code was removed, so I think no. Am I misunderstanding your question?

Previously this was iterating through each item in `data` (that is mugs that changed paths) and attempting to update all path references in this inner loop (since `seen` was keyed on mug.ufid and property the outer loop would only visit a given property at most once). The new code keys `seen` additionally on the path being replaced, and only attempts to update known changed references. So previously it was possibly doing more work than absolutely necessary by checking for path references that might not exist in the property.