Add script for updating AS/prefix tables & RS-configs

I know there are already example scripts, including one for using the API, but I thought I'd PR this in case you want to take some/all of it as an example of a quite feature-full script appropriate for cron-use (or to incorporate some of it into existing scripts). It adds things like efficiently looking up the vlan-id in the DB by vlan-number, git-versioning, emailing if changes (other than timestamp) happen, optional updating of AS/prefix table beforehand, debug-output, output to stdout or to files, etc. Maybe it's overkill for merging as an example, but let me know if some/any of it is useful, and what needs changing for the PR if so.