Add Rev Back to Rotation

[oblong]

Rev with hardmode traitor heads sounds like a lot of fun to me, the heads get a chance to make things interesting, prepare for the fight or just be mad with power. They even have their own radio channel for working together. I doubt many people will want to spend a "traitor" round hiding too. Having rev back in rotation would differentiate the head roles from the crew, and this way it's more of a fair fight and gives people a chance to do interesting stuff even in the context of a deathmatch mode.