Backtrack on Failure

[dscpsyl]

There are times when the bot can crash due to network outages or other issues. We should create a way for the bot to look through the history of the channel from the latest to the last time it sent a quote and see if there are any messages in between that need to be quoted.

This should happen:

1. Routinely, every day or so, to handle network failures
2. Everytime during startup, to handle crashes and restarts