Allow GRIB data as an example dataset

[zbruick]

Need to add support for other files than netCDF in load_dataset, namely for GRIB data, which a PR will be coming to fix shortly.

[zbruick]

And I would think support for .zarr and .hdf files may also be useful at some point down the road. While there are many ugly ways to do this, the cleanest way that @StephanSiemen and myself have thought of is to make load_dataset as general as possible, which would break the current examples by requiring the full file name, including the extension in load_dataset. Thoughts on this? @rabernat

[rabernat]

I know how to do this and will soon submit a PR to fix it.

[rabernat]

make load_dataset as general as possible, which would break the current examples by requiring the full file name, including the extension in load_dataset

The solution is to check whether name has an extension or not. If no extension, then we append .nc.

[dcherian]

Closed by #3121