Message buttons: Standup configuration

[stvnrlly]

We may not be able to provide everything via buttons, but running the initial standup creation via the message API can give users a better idea of how to configure the bot. This could include:

• Days of the week
• Audience (None, here, channel)
• Reminder times (15, 30, 60, 90)

The bot could also give instructions for more advanced configuration (which is what we provide now). The same flow could work if a user wanted to update the standup's configuration.