Add HybridSleep support and change CanSleep

Emulate the logind API to make it more easier for porting to
ConsoleKit2 for the CanSuspend/CanHibernate/CanHybridSleep methods.
They now return:
yes - system can and user explicitly authorized by polkit, rbac, or neither is running
no  - system can and user explicitly unauthorized by polkit or rbac
challenge - system can and user requires elevation via polkit
na - system does not support it (hardware or backend support missing).
The auth methods have been removed.
Currently HybridSleep only works on Linux.