examples in installation

[rpoleski]

In #121 @kingwithqueen suggested to add examples/ and subdirectories to the PiP installation, so that they can be easily run after the code is installed. I'm not sure what's done typically. I'm not sure we should be forcing everybody to have this files locally. Maybe we should have a proper error message, if examples require a file that was not downloaded.

Waiting for opinions of others.