- set PYTHONPATH inside the AppImage so libcalamares is found
- add Python module to the sample configuration
- relax password requirements (while we're at it)
- Add a script for building a Calamares AppImage file (this is
useful in *some* limited contexts, not a general way to distribute
Calamares since it's much more efficient to use installed libs).
- Add example config files for this AppImage build.
- Download the linuxdeploy tools if they are missing
- Document script flags some more