support newer versions of Ubuntu than 12.04
Change package name for libaudit based on release

Post 12.04 Ubuntu changed the name of the libaudit package. Specify
which package name for all current LTS releases and set a default for
non LTS releases.

Use release names instead of release numbers.

Also fix some linting and add tests.
Merge pull request #5 from gds-operations/fix_to_work_on_modern_ubuntus

Change package name for libaudit based on release