cryptroot: Make-good the tree

[tdewey-rpi]

Use this repo by:

mkdir -p working
python -m venv working
. working/bin/activate
pushd app
pip install -r app/requirements.txt
python3 configure.py
popd

Then

sudo ./build.sh ${configuration_name}
eg
sudo ./build.sh cryptroot_image

Make sure you've also adjusted the default parameter files - which I'll clean up in a follow-up commit

[roliver-rpi]

This looks good to me.

I've got a WIP change that pulls everything (including an appropriate venv) into a Debian package + installs files as appropriate into the filesystem; I'll rebase on top of this.