Updated for Laravel 5, plus a few minor fixes

Updated the dependencies for Laravel 5 and made sure everything worked in L5.

Added support for closing a form, which is helpful when working inside a template

Fixed getFieldOptions() so it didn't replace your classes, but just made sure that the bootstrap class was present instead.

Fixed getDefaultForm() so it returned something other then null.

Fixed some documentation errors that had drifted out of date.

Made the static field work correctly in Bootstrap land.

Note: This won't work in L4 now, as the composer dependencies will require L5, so it would probably need a major version number bump if you were to merge this in.
Please pop the `{` on the next line. I know at some point I should ditch the Laravel code style and go full PSR, but right now this just makes the method inconsistent with the rest of the file.