Fix for year zero bug and update to d3 libraries

This is the fix for issue #20. It's coming from my personal fork since it was done on my own time rather than work time.

I've also updated the d3 library files, which is probably a good idea to do anyway. d3.geo.projection.v0.min.js now seems more sensitive to the file encoding the server sets, so make sure to serve it as UTF-8.

A demo is running at http://champ.cs.sfu.ca/WikiHistory/latest/whoosh/fixyearzero/. Compare the speed against http://champ.cs.sfu.ca/WikiHistory/latest/whoosh/full/; I haven't decided if the page initialy loads slower now (which is possible due to the library changes).