Handful of updates for Campfire bot

This is kind of a grab-bag of misc. updates. A quick summary:

- Added instructions for configuring the Campfire bot to the configuration doc
- Removed some stuff from the configuration doc that didn't look like it belonged there...I think it may have been left-overs from the old configuration documentation. Let me know if I mis-interpreted that.
- I noticed an issue w/ the donate command - it didn't work, because I used the wrong function name. Fixed it in this PR.
- Switched to indexOf for command matching, as recommended by @askmike.