Add jsonview

Hi! This was mostly to scratch an itch I had with POSTMan and its inadequate code-folding capabilities. Turns out was planned for future release, as well.

https://github.com/a85/POSTMan-Chrome-Extension/issues/120#issuecomment-21583807

So, I added jsonview to the "editors". 

Please ignore the "file not found error" commit. I was having issues getting the local environment set up, and that commit accidentally creeped into the branch.

Thanks for the awesome software! I'll probably add stuff in the future as well.