samples/net/http: Add the HTTP server sample application

Add the HTTP server sample application on top of the
HTTP Parser Library.

This sample application is based on TCP and HTTP chunk
transfer code found at:

https://gerrit.zephyrproject.org/r/#/c/9977/



A README file with sample output and a detailed
description of this application is also provided.

Jira: ZEP-820
Jira: ZEP-1542
Jira: ZEP-1556

Change-Id: I649104a256190577000bbac118136d5bc21f83bf
Signed-off-by: Flavio Santes <flavio.santes@intel.com>