Update rstudio docker container to support image analysis vignette

[dlebauer]

• need to add python, terrautils
• update on workbench and DE

Update the terraref geospatial dockerfile based on terrautils requirements + python in the Cloud 9 dockerfile

This is completed when:

• The docker container is updated
• Can run all chunks in tutorial books

[Chris-Schnaufer]

Link to pull request: terraref/toolserver-dockerfiles#15

[dlebauer]

Remaining tasks:

1. test that it works
2. merge & build on dockerhub
3. as Tyson to update image used on VICE

[Chris-Schnaufer]

Building container from https://github.com/terraref/toolserver-dockerfiles/blob/master/rstudio/Dockerfile

[Chris-Schnaufer]

Remaining tasks:

• Merge branches into master (top branch is updated-for-python3-only)
• Make official build onto dockerhub: terraref/rstudio-terraref:latest and terraref/rstudio-terraref:2.0
• Item 3. from dlbauer comment above (place instance on VICE)