Install Landlab from source in develop kernel

[mdpiper]

In the Develop kernel of the jupyter and frontier Hubs, the current version of Landlab (v2.5) is installed from conda-forge. Instead, Landlab should be installed from source in this kernel, and refreshed regularly, so the most current updates are available to developers.

[mdpiper]

This is a request from @sebastien-lenard and @loroberge.

[mdpiper]

One problem with this is that there are near-daily updates to the Landlab source, so this won't be sustainable because of the labor involved.

My thinking is to have users clone the Landlab repo into their home directory on the Hub and install it from there, locally, in their userspace. The user can pull changes from upstream any time and reinstall to keep Landlab up to date.