Major file restructuring

Quickly getting out of hand here as I turn it into a one page app
Checks for presence of existing session

Amount of code to manipulate the DOM quickly getting out of hand!
Reverted addBeer functionality

Returned to using original addBeer functionality until more robust
solution written
Now uses addBeersBetter

Looks like some kind of weird issue when using FormData and GET… worked
A-OK when POST.
All server-side functions now using upgraded AJAX function
Added readme to describe project