Move Dr_Dubz art link detection to config files

[CPColin]

Continuing from #727, move the Dr_Dubz art detection to the config files so we can add more of them without having to do software releases. We should try to make it so you can specify a username and a regex in the YAML, followed by the usual list of responses (with weights) that Tracker could say.

Matt suggested we could add a chance of Tracker making fun of DoctorSmasher for talking about Shaktool. We could also add one for DragonCapman posting art during Pink's streams (or tell her how to add them herself).