Fix broken date parsing

- Months of '09' and '08' were being parsed to 0 in Firefox and PhantomJS (and possibly others).
- Added more granular tests

Issue is here: https://code.google.com/p/chromium/issues/detail?id=146163

Ideally this should be merged in right away but it looks like there's stuff that was removed from the old built version of bluebutton.js that this is adding back in. I think we need to remove that stuff from the source. I can pull it out and add it to this PR.