Be able to act on issues other than the current one

[tehsmyers]

Probably need to create a filter; if the first arg to a call is an issue (e.g. #1234), record that call as acting on the issue in the first arg, like "!suggest #1234 do something". This would likely require more fanciness with meetbot than we're currently doing right now, and might even be impossible, since it would involve adding information to meeting topics that are no longer active. It all depends on how meetbot stores the minutes entries.