Reverted change to mathchColor in attempt to fix choropleth coloring bug.

We're using folium on a project, [bikeability](https://github.com/cfa-nm/bikeability) (THANKS!) and it seems that a change made in commit 8269f81b0b932f49a76bc20412b47a939805dab3 has caused our choropleths to turn out all grey.

The images below are the before/after shots of the same map.

![map-ok](https://f.cloud.github.com/assets/747219/1222713/19999092-2700-11e3-988f-51b349107cc4.png)
![map-notok](https://f.cloud.github.com/assets/747219/1222712/19877cd6-2700-11e3-841d-116e44f26cb4.png)

By changing the line below back to what it was our chorpleths are nice and colorful again.