Remove dependency of FormField package

In this release, we remove the dependency of luthfi/formfield package. So the package will generate basic html structure on each view creations.

Changelog:

• Use singular entity on controller name, eg. VehicleController instead of VehiclesController.
• Remove FormField class facade usage. Now this package will generate views in plain html markup.
• The FormField version of views and forms still can be generated by passing --formfield command option.

$ php artisan make:crud Vehicle --formfield