Fixes Nitrogen is not defined

Hi Jesse,
playing with last changes, I found when you enter to index page, this error appears:

ReferenceError: Nitrogen is not defined
...NbH2jsTvzT4atAFUYFl4OA93v4e1GuDfZXWjiItuUbSUO-eqd6H_hu_h6D_mT63OPwcgEXrmkLwRmRew...
localhost:8000 (línea 26)

TypeError: a.value is undefined
...ass.prototype.encode_binary=function(a){return this.BINARY+this.int_to_bytes(a.v...
bert.min.js (línea 1, col 3192)

and the click button event doesn't work. Just putting the object creation outside the document.ready() fixed it.

One thing I realized after making this change is the destroy you commented in nitrogen_jqm.js. Because of taking the object creation outside the document.ready() and the condition, maybe is needed to make the condition in the object creation too or uncommenting the destroy again. What do you think?