Plat 556 http rest proxy watching

When using this to watch (eg, etcd) it's difficult for debugging to have to catch exceptions, and we need to get data as it comes, not only once the connection is closed.

These changes allow for the HTTP Rest Proxy to be used in this context.
For the case when we are connecting to a chunked HTTP stream (which has infinite length), this is necessary.  The way I use it is pretty much synchronous and already had a HttpRestProxy present.  I think HttpClient would be overkill for this very lightweight scenario, plus it would require rewriting of the client code.