HydroShare Binder - Baseimage Example

This is an example for making a HydroShare resource \"Binder Capable\" by extending the HydroShare Ubuntu image. There are several advantages to using this base image:

1. Binder configurations can use Dockerfiles in addition to all other configuration files, e.g. apt.txt, requirements.txt, postbuild, etc.
2. The image is preinstalled with JupyterHub, Python3, and tools for accessing HydroShare data (e.g. iRODs, hs_restclient, nbfetch, and hstools) to facilitate interaction with the CUAHSI HydroShare.