Fix artisan route to show multiple route verbs

"artisan route" only shows a single verb per route method. This is misleading when routes are defined with multiple verbs to a single method/endpoint, for example with Route::match().

Fixed by imploding the methods array for the command output and removing HEAD where necessary.

nb. not tested exhaustively but works with a combination of resource, controller and closure routes. I'm uncertain about cases where this approach might skew artisan route output, and have not tested with filters.