Enabled composer autoloading

I don't use this extension, but someone from the Nette forum has a problem installing it (see http://forum.nette.org/cs/16277-jak-spravne-pripojit-extension-k-nette-pomoci-composeru).

It's simply wrong to use RobotLoader to autoload composer packages. Never ever rely on that. The vendor directory where composer packages are downloaded to should never be indexed by RobotLoader.

For example I don't use RobotLoader at all even though I use Nette.