Socks-rtc and tcp rewritten, code re-organized, uses uproxy-lib build style, uses new logging

This is a significant chunk of work (towards workstream https://github.com/uProxy/uproxy/issues/335), probably best to look at a checkout rather than diffs.
 
Outline:
 * Socks-rtc, rtc-net and tcp have been rewritten and are much more robust.
 * code re-organized to use the uproxy-lib build style, and use it's build rules.
 * uses new standardized logging
 * replaces: 
   * https://github.com/uProxy/uproxy-networking/pull/94
   * https://github.com/uProxy/uproxy-networking/pull/97 

TESTED: 
manually ran: 
 * src/echo-server/samples/echo-server-chromeapp
 * src/socks-rtc-net/samples/socks-rtc-net-freedom-chromeapp

Reviewed by pair-review session with trevj for the :+1: 

Next Steps: 
 * Make socks-rtc-net-freedom-firefoxapp work
 * Provide freedom wrappers to use this in uProxy (or directly use it as is in uproxy module)
 * Write a chat2 style copy-and-paste proxy sample 

Note: Depends on:
 * https://github.com/freedomjs/freedom/pull/100
 * https://github.com/freedomjs/freedom-for-chrome/pull/27
 * https://github.com/uProxy/uproxy-lib/pull/54
So, +1 for moving the echo server out of the SOCKS test app.

However, this new app is really weird. This `server` member variable implies there can only be one instance. In that case, why have the constructor? I feel you're over-complicating an app that needs to be as simple as possible.