Add support for RequireJS, AMD modules and a global Backbone.Form object

[whatyoubendoing]

[powmedia]

I want to merge this in but need to make sure it's all working as expected. Have you got this working with your setup? I have added the beginnings of an example AMD setup in examples/amd but haven't been able to get it working yet (I use Browserify so my requirejs knowledge is limited).

I've pushed this example in to the branch b3njamin-master; can you fork this and get it working and we can then make sure everything works before merging? You should be able to open the example/amd/index.html file in your browser and see a form, but none of the modules are being included at the moment.

Note: I've removed the require('jquery') lines because we should be using Backbone.$ in case the end user has decided on Zepto etc. instead.