tutorial vs 'release' checkouts

[briandobbins]

In order to address the immediate issues with the tutorial, I've updated the documentation to download a new tag ('cesm2.1.5_tutorial'). This advice works great for the tutorial, but is not correct for general use - eg, it uses a specific 'tutorial' routing queue, and defaults to a tutorial-specific project code. Both will be problematic in regular, non-tutorial use.

We need to update the material to reflect this, but we can do that later.