Bug#1094965: wtmpdb: provides no way to prune rotated logs

[Andrew Bower <andrew@bower.uk>]

Package: wtmpdb
Version: 0.13.0-5
Severity: normal

wtmpdb will rotate logs but nothing will prune them (like logrotate would for
other types of log - unfortunately it doesn't fit in well with the wtmpdb way).

Also logs shouldn't be in a state directory like /var/lib. We can forgive the
live database being there, perhaps.

One solution I have in mind is:

 - add 'wtmpdb rotate --dest DIR' option
 - change timer/cron files to dump rotated files in /var/log
 - after rotation, prune files keeping a minimum age and count
 - configuration is by editing the unit/cron files

I think we can set some long defaults - we just don't want unbounded
accumulation!