Add pre compiled binaries for windows, mac and linux

Adds pre compiled binaries for all 3 major platforms using node-pre-gyp. This is the same thing we did and are using in node-serialport and has worked great so far, we also have PR pending that does the same for node-opencv.

@creationix after merging I do need your help to generate the secure keys in travis and app-veyor (since they are repo and account bound respectively). We also need to create a new branch for OSX pre-compiled binaries called osx-binaries, since travis does not support multiple OS builds, so we need a different branch to compile for OSX.

I'm creating a publishing-binaries.md file to describe the process, I'll added a make task to make it easier to generate the binaries with each release.

BTW we at The Hybrid Group is sponsoring the AS3 buckets, we are also doing it for node-serialport (as mentioned above) and we'll be adding them for node-opencv shortly.

Regards,