Issue #54 - Addition of support for sending binary data (Android only)

This is a submission for inclusion to resolve issue #54.

It also provides and interface for issue #53, but no implementation for any platform other than Android.

I've added a new function, sendBinary, as I proposed in issue #54, and documented this in README.md.

I have done basic sanity testing, and it works, but I haven't tested all exception cases.