Bug 7240: Cleaning up import tables and action_logs

Bug 7240: Cleaning up import tables and action_logs

This patch lets cleanup_database also purge older records from the (five) import tables and the action_logs table.
Two new command line parameters are introduced: --import and --logs.
If no number of days is specified for --zebraqueue, --import or --logs, it defaults to 30 days, 60 days resp. 180 days.
I did not add a default for --sessdays, because this parameter cannot be seen separately from parameter --sessions.

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Adds new parameters and code, does not change existing behaviour

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>