Allowed the globe keyword to PlateCarree.

I wanted to create an example to demonstrate choosing the wrong ellipse for your data - this involved upgrading the Globe's proj4 definition - as it turns out the arguments are order sensitive.

This work has helped me understand the proj4 datum/ellipse peculiarities and will allow follow on work to rationalise the interface in cartopy. That is not for here though (I just wanted to produce a pretty picture!).

![example output](https://f.cloud.github.com/assets/810663/1096510/7b837e22-1700-11e3-9481-dc468ad35fb0.png)