Consistent boilerplate code in Sandcastle demos

Some Sandcastle examples use outdated or inconsistent boilerplate code. This can be fixed be clicking the Save As button in each demo and replacing the code.

This would make a good beginner issue.

More details and an example from @emackey in https://github.com/AnalyticalGraphicsInc/cesium/pull/6337/

The other changes here are just from re-saving the demo directly from a Sandcastle instance. Would be great to have an intern go through and re-save all the demos at some point, so the boilerplate code all matches what Sandcastle produces (or write a build script to do it).