Xeno changes, bug fixes

Changes:
1) Flips the Xeno shuttle around.
2) The Gamma armory is now opened and the nuclear code is provided when the Xeno:Crew ratio hits 3:1.
3) When the remaining crew is killed on the shuttle while it is heading to CentCom, the Xenos will still complete their objective.
4) Weeds will now decay when their weed node is destroyed.
5) Properly gives the magistrate access to his own office.
6) Fixes an incorrect message on secbots introduced in the last patch.