Ticket #43: Fix equals() for Message

Change-Id: I25a1c49548fa5e9507f94e81d1a69da9e7b2bf63
Reviewed-on: http://naan.mimuw.edu.pl:8001/119
Tested-by: Nebulostore Nebulostore <nebulostore@gmail.com>
Reviewed-by: Krzysztof Rzadca <krzadca@mimuw.edu.pl>