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

test/IXGetFreePort.h

@@ -0,0 +1,12 @@
+/*
+ *  IXGetFreePort.h
+ *  Author: Benjamin Sergeant
+ *  Copyright (c) 2019 Machine Zone. All rights reserved.
+ */
+
+#pragma once
+
+namespace ix
+{
+    int getFreePort();
+} // namespace ix