For package installation, the runner $TMPDIR may not be big enough, eg
when rebuilding an initramfs it runs out of space, so use a new function
that sets it explicitly.
- Depends on being run inside vagrant
- Installs dependencies automatically
- Environment is fully reset for each test
- Adds testcases for backupninja and sys handler
- Docs are missing but will be added
Two tests are currently failing due to two bugs, one of which has gone
unreported.
