loadStrings() and loadJSON() fixes for preload()

I incorporated brysonian's loadJSON function and approach to preload()
(linked below) so that loadStrings and loadJSON work in preload without
callbacks.

https://gist.github.com/brysonian/7298465
https://github.com/lmccart/p5.js/issues/81
Update p5.js

added a semicolon
Cleanup