gupnp-tools: new package

gupnp-tools: new package

GUPnP Tools are free replacements of Intel UPnP tools that use
GUPnP. They provides client and server side tools which enable
one to easily test and debug one's UPnP devices and control
points.

http://www.gupnp.org/

Signed-off-by: Fabrice Fontaine <fabrice.fontaine@orange.com>
[Thomas:
 - use "depends on BR2_PACKAGE_LIBGTK3" instead of a select, and
   simplify the Config.in comments consequently.
 - move from "Development tools" to "Networking applications"
 - license is GPLv2+, not LGPLv2+.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>