Add leading slash if missing in route patterns

[vlakoff]

This PR allows to omit the leading slash when defining routes.

For the record, I have a lot of routes like so:

$app->get('/about', function () {
    return view('about');
});

[coveralls]

Coverage increased (+0.003%) to 97.183% when pulling 50e06be on vlakoff:routing into 1dedd25 on slimphp:3.x.

[vlakoff]

Wow, that's an impressive testing suite!

[mathmarques]

Route pattern is just a simple concatenation. See this for more information.

Slim used to do the way you proposed, but it's better without all the "magic".

[vlakoff]

Yes this "no magic" approach seems to have many advantages. I'll live with the leading slash.

Thanks for pointing this out.