Removed bug related "compatibility" hack

Development version of QA Dashboard now understands bugs as an array of
objects. The other hacks are still needed but shouldn't be for long.
Don't replace HTML when editing test cases

Previously editing test case comments received HTML fragment from
backend and placed that in the table cell. This fragment did not however
have the edit mode set and thus re-editing a comment did not work
properly (input was empty).

Now just return HTTP 200 OK from the backend and remove the form element
in the frontend so the markup formatted comments is not lost.