Relay prototype

Considering getting this simple relay implementation into ThaliProject while I finish up the other aspects of it - to simplify folks using the HTML5 seed.   Perhaps into a new branch on ThaliProject - but then you wouldn't be able to see the diff for review.

Only one source file here for the relay - RelayWebServer.java (and RelayWebServerTest.java).  The other bits are all NanoHTTPD.  Open questions on code file headers for those....
I'm sooo confused! Why didn't you just call getInputStream? It's supposed to give you an input stream with the request body which you can then stick in an Apache InputStreamEntity and hand it to the Apache client. Why go through materializing the entire request body in memory?