Modified active mod directory to orrect one, changed handling pull requests.

Opening steam URLs only opened browser for me, so I changed it to (I hope) more universal way. 

Active mod data should be directly in addons/d2moddin. With these changes client should work (at least pudgewars) if mod is downloaded to d2moddin/<modname> and gameinfo.txt isn't somehow corrupted (I had problems with whitespaces when I first changed that, there is mine http://pastebin.com/ZJh4nsHd and worked for me).

Btw. It's my first pull request so be gentle :)