Add git lfs to the corn base image

[asteiker]

To support Harmony service testing, I am hoping to use the Openscapes 2i2c JupyterHub to run tests in this repo: https://github.com/nasa/harmony-regression-tests. This repo now requires the use of git-lfs to manage the large reference files stored there. It would be great if git-lfs were supported in our hub so that I can use it moving forward instead of locally. I chatted with @betolink briefly and it sounds like this could be rolled into the next release this week if possible. Thanks for your help!