kore 1.2 (new formula)

This commit add's a new formular to Homebrew for Kore. Kore is a fast
SPDY capable web server for web development in C.

Look at https://kore.io/ for further information.
I don't actually know. It could be intended by the creator of Kore. It also uses another library to link, ```pthreads```. Someone could not want to have Kore build with that.