Changing keyboard mapping so it will not conflic with pep-8 checker.

Cannot assign Shift-Cmd-P to PrettyJson.MakePrettyJson. It is already assigned to python-pep8.run /command/KeyBindingManager.js:463

I assume that Shift-Ctrl-J should be ok for this. Initially, i was thinking of B as it comes from beautiful but that is used by a Bower extension. J comes from JSON and i couldn't find any conflict.