process_mission_votes: Lock decisions

Otherwise, a player may send an extra !mission or !excalibur or !sheath
and break the game (by causing the round to count twice).

Fixes #6
Merge pull request #16 from an1itdp01y/lockdecisions

process_mission_votes: Lock decisions
Implement Trapper

Closes #17
Merge pull request #26 from an1itdp01y/trapper

Implement Trapper
Split team prpoosal and vote into separate methods
Add test methods to blaze through games
excalibur can't be given to team leader, not sender

Does this matter? Isn't the team leader the only one able to assign? Ah,
not if I'm in test mode!!!
allow nil debug team vote
prompt for trapper in !test team
!test team: Allow specifying mission votes by player