ADD: Tcp connector

= DONE
== Socket connectors

 * Create SocketClient and SocketServer connectors that can be used for JSON-RPC via TCP socket (not really sure UDP is sufficient but can be activated).
* Server can be configured to handle multiple connections at the same time. By default, it only handle one connection at a time.
* Compilation of Socket connectors is conditioned with SOCKET_CONNECTOR CMake variable.

== Fix

I have corrected the way connectors headers are installed

== Improvement

Library dependency uppon pthread is integrated into CMake configuration using Threads package

= TODO

Refactor to use Windows thread instead of pthread on Windows platforms