Landsat example with all hvplot graphics

[rsignell-usgs]

@scottyhq and @rabernat, partly to bone up on my hvplot/pyviz skills, I replaced all the plots in the Landsat NDVI notebook with hvplot interactive graphics here.

Not sure whether you want this as a PR or how best to handle it, but just wanted to let you know since it's pretty cool. For, example, when live, you can zoom on one of the small multiple plots, and all the plots zoom together:

Thanks to the pangeo binder instance, you can also run the notebook live: