CentOS compatibility

**Added Centos compatibility**.
- Check-sums.
- RHEL package URLs.
- YUM package manager.
- Test-Kitchen CentOS platform.

**Improvements**:
- Idempotent package installation / log file touching.

Please see commits for comments.

I can't seem to create a pull request onto develop. Luckily master/develop are on the same commit, please merge develop if accepted.