Added the iPOPO waiting list service

A waiting list which instantiates components as soon as their factories
are available.
This service is provided by a bundle, not a component, so the list of
waiting components is kept even when the iPOPO core bundle is updated
(or started lately).
The Remote Services sample uses the iPOPO waiting list

This allows to easily update implementations and play with components
without manually instantiating components nor using IPOPO_AUTO_RESTART