samples/net: DNS client application

This sample code shows how to write a DNS client application.
Only client functionality is implemented in this sample.

The code is self-documented. Read the README file for more information
about the network setup.

See https://tools.ietf.org/html/rfc1035

 for more information about the
DNS protocol.

Origin: Original

Jira: ZEP-500
Jira: ZEP-501

Change-Id: Ibcfa4e392143fdc2258971304d5296d70c1c9423
Signed-off-by: Flavio Santes <flavio.santes@intel.com>