tools: Add destination is group option to dtntracepath
daemon: Reverse Path Epidemic for Non-Singleton Bundles in Prophet Routing

Prophet routing no longer handles group / non-singleton bundles like epidemic. Instead
the it checks if the peer knows the way back to the source of the bundle using the
probability set of the peer. Only if the peer knows the way back, the non-singleton
bundle is forwarded.
daemon: Fixed typos
daemon: Added exception catching for persistent store of the peer probability set