By: Addison Wylie “Oh boy. We’re really in ‘it’ now,” I thought as I watched Jon S. Baird’s crackpot dark comedy about decrepit Detective Sergeant Bruce Robertson fighting for a promotion and doing anything he can to guarantee the position.  If he has to backstab, manipulate, and cause scenes, he’ll gleefully do so. Baird, who wrote and adapted the screenplay from Irvine Welsh’s book of the same name, is just as game as Robertson when…