Introduced Recipient implentation classes:

Introduced Recipient implentation classes:
- DirectRecipient: A direct session id that needs solving into an ip:port
  combination
- DhtRecipient: A virtual recipient that will cause querying the local DHT
  data for possible recipients (unfinished)
- SelfRecipient: A virtual recipient, yet direct one, as this will be resolved
  into *this* own node's session id
- UpperRecipient A virtual recipient for all boot, master and list node's
  session ids
- Internal TODO for above closed (and nicely solved)