Promoted @am11 to project lead

@am11 has put a huge amount of working into node-sass over the past few months, perfectly bridging the two worlds of C++ and Node as well as making Windows a first class citizen, I'm very happy to be passing the torch over to him to lead the way. :tada: 

I'll still lurking around, building binaries where needed etc but won't be involved with day to day decisions as much now. :rabbit: