PolicyContext: introduce new interface
PolicyContext: introduce new interface

A PolicyContext allows to abstract the application code from the
real policy framework requirements. The AbstractPolicyContext
is to simplify various implementations.

Signed-off-by: Jan Viktorin <3eab6ac54c005c4408f608556a6663b7f2abede7@fit.vutbr.cz>

BeeeOn/server,BeeeOn/server,BeeeOn/server,BeeeOn/server