Add Treasury

This is not a pretty one, but it seems to work. There are a few different report listing pages, which all have slightly different markup.

While working on this, I also learned about the [Treasury Inspector General for Tax Administration](http://www.treasury.gov/tigta/about.shtml) which seems to be a separate IG that is also part of Treasury, but specifically tasked with IRS oversight. I think this should probably be treated as a separate scraper, but wanted to make the note here so it doesn't fall through the cracks.