Refactor routing package

- Create separate package for plain socket routing
- Remove getExecutor from MessageSender

Change-Id: I60f1219d38e11550d17c9a644d8acf0238eb6dc2
Reviewed-on: http://naan.mimuw.edu.pl:8001/80
Tested-by: Nebulostore Nebulostore <nebulostore@gmail.com>
Reviewed-by: Bolek Kulbabinski <bkulbabinski@gmail.com>