Initial migration to new socks-rtc and rtc-net

 * Updated package to use this version of uproxy-networking: https://github.com/uProxy/uproxy-networking/pull/119 also to avoid using the broken 11.0.1 version of uproxy-lib
 * renamed uproxy.json to be freedom-module.json (to fit standard style for freedom-modules)
 * Removed global socks-to-rtc and rtc-to-net modules & replaced then with remote-instance-specific instances of the socks-to-rtc and rtc-to-net classes that are constructed as/when they are needed. This removes the need to any peer-information to be in the signalling messages (PeerSignal should now just be a WebRtc Signal Message)  
 * Added instance-level configuration for socks-to-rtc and rtc-to-net.
 * Added closing of the rtc-to-net module when the access is revoked. 
 * Added notification for when rtc-to-net closes. 

Still to do: 
 * use dynamic port (https://github.com/uProxy/uproxy/issues/367)
In the past we only had one RtcToNet object, even if the user was acting as a proxy server on behalf of multiple clients.  Since RtcToNet already knows how to manage multiple WebRtc connections, make requests on their behalf, and not mix up the responses, it seems like we should continue to use one RtcToNet object shared for all users we are giving access to.  Otherwise it seems like we would be a bit wasteful.  Alternatively if we really like having one RtcToNet object per user, maybe we should refactor the RtcToNet class in uproxy-transport to only allow for one webrtc connection?

Adding @trevj for thoughts...