cfgfile: library to interpret config files

cfgfile: library to interpret config files

This library provides a tool to interpret config files that have
standard structure.

It is used by the Packet Framework examples/ip_pipeline sample application.

It originates from examples/qos_sched sample application and now it makes
this code available as a library for other sample applications to use.
The code duplication with qos_sched sample app to be addressed later.

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
Acked-by: Pablo de Lara Guarch <pablo.de.lara.guarch@intel.com>
Acked by: Ivan Boule <ivan.boule@6wind.com>