When exiting diff mode from an interp, jump to the first subterp

* Pegs jquery to 1.11.0 (so we don't get betas)
* Adds an element to the context to know what the first subterp is when exiting diff mode
* Generates a url for that subterp if starting in an interp diff
* Updates JS to use that first subterp url if navigating diffs via ajax