Add BedMachine Data to fetch

[Matt Tankersley]

Description of the desired feature:

Add the Bedmachine dataset as a fetch call. Either figure out how to use authentication from NSIDC or use the following link from here

https://storage.googleapis.com/ldeo-glaciology/bedmachine/BedMachineAntarctica_2019-11-05_v01.nc

Are you willing to help implement and maintain this feature?

[Matt Tankersley]

This notebook uses Pangeo to load the data.

from intake import open_catalog

cat = open_catalog('https://raw.githubusercontent.com/ldeo-glaciology/pangeo-bedmachine/master/bedmachine.yaml')
ds  = cat["bedmachine"].to_dask()

[Matt Tankersley]

Closed for now with 3813d99, might eventually fetch directly from NSIDC, but that will require figuring out how to ask users for login info during the pooch.fetch call.