Gem now builds

Scott, hello. I was delighted to find your branch of the Pusher client, since the others depend on broken libwebsocket and don't function correctly. I was pulling my hair out -- so thank you.

I'd like to offer this pull request; let me know what you think. The changes don't alter the Pusher functionality at all, but instead allow the Gem to be built locally. The process is documented in the README.