Feature/httpd (#94)

* Stub code for http server

* can send a response, cannot process body yet

* write headers to the response

* remove commented code

* add simple test + set default http handler

* tweak CI + unittest

* add missing file

* rewrite http::trim in a simple way

* doc

ixwebsocket/IXSocketServer.cpp

@@ -11,7 +11,6 @@
 
 #include <iostream>
 #include <sstream>
-#include <future>
 #include <string.h>
 #include <assert.h>