Kthresher

Added
- Only create a syslog handler if /dev/log exists.
- Reference of unattended-updates capability to remove unused kernels.

Changed
- Use package section from `Version` instead of `Package`.

Added
- Add system logs on purge, show and errors.
- Python3 Support.
- Add systemd timer units.

Changed
- Documented default values.
- Make show autoremoval action the default.
- Use `version_compare` from `apt` when `LooseVersion` fails.

Fixed
- Make `keep` truly default to 1.
- Cron job should not fail if the binary does not exist.

Removed
- Setuptools does not include `data_files` with man page nor default config anymore.

Added
- Removed shell from bash completion.
- Added license to bash completion.

Added
- Bash completion

Changed
- Support to most/all kernel/header packages [flavors used in Ubuntu](https://people.canonical.com/~kernel/info/kernel-version-pockets.txt)
- Using logging consistently.
- PEP8 compliant.

Added
- Better error handling when executing as non-root.
- Logos.

Changed
- Regex to include linux-headers ending in -common.
- Improved the testing example on the README.

Added
- Support to amd64 kernels.

Changed
- Consistency between `--show` and `--purge`.
- Sytle improvements(pep8).
- Man page update.