John Adrain is a lukewarm fan of Stephen Colbert, the cable-TV comedian who slices up hypocritical politicians and skewers fat cats on his popular show “The Colbert Report.” But Adrain is singing Colbert’s praises this month. A segment last week on Colbert’s show featured Adrain and his Bed Bunker, a 1,300-pound steel gun case that sits under a queen bed in place of box springs. Colbert’s producers featured a clip from Adrain’s business website in which the Spokane inventor pulls out a shotgun from the safe, cocks it with one hand and smiles at the….