[HTML1] Navy Secretary Ray Mabus spent about five minutes with Stephen Colbert on Thursday, but the two entertainment icons — one’s taking over for David Letterman next year, the other had a role in “Battleship” — packed a lot of big issues into one quick interview. A sampling: Post-service careers: Colbert asked Mabus, who left uniformed Navy service as a lieutenant junior grade, whether he ever wished he could go back in time to his former self and say, “Hang in their, buddy — you get to boss these people around later.” Recruiting and retention: Mabus offered his favorite recruiting poster…