daemon: Add corresponding EID to transfer aquisition debug message
daemon: Fix bundle transfer release bug

If neighbor was unavailable and a transfer was completed in the meantime, the transfer
was not released in the neighbor entry. This patch modifies the get() method of the
neighbor database to return cached neighbor entries even if the neighbor is not available.
For those callers who need the old behavior, an additional parameter has been introduced
which must be set to true in those cases.
daemon: Add setPeerEID() method to DatagramConnection
daemon: Shutdown a DatagramConnection if the neighbor went unavailable
daemon: Exit any loops in DatagramConnection on shutdown