Bootstrap 3 upgrade

* Change column classes to be all that 'col-md-n' business instead of 'spanN'
* Change modals to have some extra classes
* Plop in the new simple_form_bootstrap wrapper stuff
* Use datatables' bootstrap 3 styles instead of bootstrap 2
* Restyle all forms to have .form-control etc where needed
* Tweak anything with height+padding to consider border-box sizing