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....
Actually chunked transfer is a hop by hop header. So it doesn't matter if the incoming request is chunked. That is handled by nanohttpd and doesn't affect how we return the response.

That having been said we should ALWAYS use chunked transfer on our responses since it prevents us from having to queue up the whole response in memory before sending it. So please pull response.setChunkedTransfer out of the for statement and instead just plunk it right down somewhere around line 192 so it's always true.