Create a sandcastle example showing basic measurement and usage of Geodesic

Here are some starting points:

http://cesiumjs.org/Cesium/Apps/Sandcastle/?src=Hello%20World.html&label=Showcases&gist=e1fe0fd7816b924bfbec5e06b0d6975e

http://cesiumjs.org/Cesium/Apps/Sandcastle/index.html?src=Hello%20World.html&label=Showcases&gist=5b8a00c55318737f13951039166cf588

Start with the two linked Cesium Sandcastle Hello World examples and use them to understand the expected example structure. Create a Sandcastle example that demonstrates basic measurement and usage of Geodesic; done means the example runs and visibly shows those basics.

Written by the indexing model from the issue text.