Add a command to notify a user when the build queue is idle

[jdm]

Similar to 459b4a6, sometimes we want to perform some CI maintenance when there are no active build jobs. We should add a command that pings a user the next time that the queue becomes idle (and check the queue more frequently than once an hour when someone is waiting to be pinged).

[IanHibbert]

Hi, can I work on this?

[jdm]

Please do! Ask questions if there's anything that's unclear!

[jdm]

@IanHibbert Have you made any progress with this?

[IanHibbert]

Sort of, I can talk to the bot if that counts for something.
I'm having trouble figuring out how to store users who want to be pinged.
Do I have to add a ping to the PingStorage object after the command is issued?

My current implementation:

1. adds a user to an array after the command is issued
2. checks if the queue is idle every 10min if people users are in the array
3. messages a user with bot.say(user, "The queue is idle!) if the queue is idle

[jdm]

PingStorage is used for recording messages for users that are not currently in the channel, so I don't think that will be useful. Your current implementation sounds like it does what we want!