Pip install reprozip into virtual environment

[craig-willis]

Problem Our current approach using the pyinstaller/static build of reprozip fails in rocker/geospatial images with error (locale.Error: unsupported locale setting). Instead of trying to maintain a static build of reprozip, we agreed that it makes sense to install into a virtualenv via pip. Unfortunately rocker images also do not have pip/venv installed...

Approach This PR updates the WholeTaleBuildPack and WholeTaleRBuildPack classes to apt install required dependencies (libsqlite3-dev, python3-pip, python3-venv) then creating a venv and installing reprozip.

To Test

• Create an R tale and build the image. Image build should succeed without the locale error.
• Optionally create and run a recorded run and confirm that reprozip executes as expected.
• Do the same for Jupyter-based tale

[craig-willis]

https://github.com/whole-tale/repo2docker_wholetale/pull/32 is better for now.