Batch iplog and locationlog deletion

Description
-----------
Batch the amount of rows that get are deleted from the iplog and location log to reduce the table locks.

Impacts
-------
This reduces the time spent deleting records in pfmon.
This could lead to have more stale records.
An additional cronjob at night could be used to cleanup tables.

For example have of an additional hour of cleaning during the night
========cron_cleanup_iplog============

use pf::config;
use pf::iplog;

iplog_cleanup( $Config{'expire'}{'iplog'} ,$Config{maintenance}{iplog_cleanup_batch}, 3600);

========cron_cleanup_iplog============


Delete branch after merge
-------------------------
NO
Because we already have it in another index.
KEY `mac_view_open` (`mac`, `end_time`)

Since it is the first in the index it make no sense to index it twice.

http://dev.mysql.com/doc/refman/5.0/en/multiple-column-indexes.html