Jupyter notebook examples now available in Binder

[jonmjoyce]

I've added a link on the main README to Binder which will open a Jupyter notebook environment for testing out some of the functionality. You can also reach it here

I was having some trouble reaching the Netcdf DAP endpoints but the zarr/datashader/xarray stack seems to work well on Binder.

As always, feel free to contribute your own examples, modify the existing ones, and ask questions in the discussion boards!