Add topic modification support

Now that we have on call details and such, we can automatically update the topic when updating the deploy queue.  For now, it's pretty basic: it takes the two current teams the work in the dev room and uses those for the topic updates.

I expect to move this to a topic handler library later, so we can use it across all the chat rooms :smiley_cat: 

Tagging @doomspork / @jmacadam for review.