UMD: Better support for CommonJS.
UMD: Better support for CommonJS.

Closes #1838. Fixes #1829, #1834.

jquery-validation/jquery-validation,Arkni/jquery-validation,MeteorAdminz/jquery-validation,jzaefferer/jquery-validation,Arkni/jquery-validation,jzaefferer/jquery-validation,RobJohnston/jquery-validation,jquery-validation/jquery-validation,MeteorAdminz/jquery-validation,RobJohnston/jquery-validation,staabm/jquery-validation,jzaefferer/jquery-validation,staabm/jquery-validation