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Fixed some documentation errors that had drifted out of date.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 use Laravel-style docblocks (that is, lining up arguments. Double space after `@param`, single space after `@return`) as is done in the rest of the file.