Message for choose_time with too few

[jonthegeek]

When fewer than 5 total people have chosen a time, the message should look for more people in the channel. Something like this:

@current people: You have all indicated interest in joining this cohort, but we need at least one more person before the club can launch.

@here If you're in this channel, you must have some interest in joining a cohort. Please indicate your available times in the app (URL) (especially any green times -- the shading indicates how many people have chosen that time).

I'll check again next Saturday to see if we are ready to launch!