Use rocker/binder as base docker image

[florianm]

Feature

Can we build a single ruODK Docker image that runs both on BinderHub as well as standalone via https://hub.docker.com/r/rocker/binder?

• [x] Modify and test Dockerfile - local and binderhub, Jupyter and RStudio
• [x] Add tutorial workbooks (ipynb and Rnw) to inst/binder