Add trailing slash to remove redirects.

[tobinjt]

When you request /tags/foo, the web server will redirect you to
/tags/foo/ so the browser needs to make two requests. Add the trailing
slash in the link so that only one request is needed.

[crachel]

Also needs it for /categories/foo/ since both point to directories.

[tobinjt]

Also needs it for /categories/foo/ since both point to directories.

Good point, added. Thanks :)

[luizdepra]

Hmm... I need to check if there is a better way to solve this problem ratter than concatenating a /.

[luizdepra]

@tobinjt, I just suggested two fixes.
Also, add yourself into CONTRIBUTORS.md.

[tobinjt]

I've accepted those two fixes and added myself to CONTRIBUTORS.md, thanks!

[luizdepra]

Thanks. :)