Return the entire traceback when an error is encountered.

This catches me quite often.  I use jsonapi in my own product, to expose several functions.  When a user sends strange parameters in the request, an error is returned such as "{u'runtime': 0.007885932922363281, u'success': False, u'error': u'list index out of range'}" - this is not enough information for me to fix the error.

I know that printing the entire \\n-separated traceback is not pretty, but it certainly makes my life easier, and I hope that you can include this in the next release...