Fix registering package routes

[mortza]

After second installation of latest commit (I tried just latest commit) I've noticed that the option use_package_routes and url_prefix is useless and we should register routes manually in web.php file (or any other file used to register routes) even when use_package_routes is set to true.

so I edited boot method of LaravelFilemanagerServiceProvider to register routes if corresponding option is enabled and routes from Lfm to register routes using url_prefix option.

[streamtw]

Thanks @mortza !