examples/service_cores: add new sample application

examples/service_cores: add new sample application

This commit adds a new sample app, which showcases the value
of running services. In particular it allows the application
to dynamically schedule services to service-cores.

The sample app itself registers a number of dummy services,
and applies different profiles to them at runtime. Note that
this sample application does not forward any traffic - it
demonstrates advanced usage of the service cores API.

Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Gage Eads <gage.eads@intel.com>