Initial skeleton for v1.3.0. Currently contains the Message_type enum and the Hello message.
Merge branch 'master' into akron/v1.3.0
Added v1.1 and v1.2 directories with some stubbed out message.* files. Also updated the Message_type enum names to reflect v1.0's.
Merge remote-tracking branch 'origin/akron/v1.3.0'