Add option to remove Chkservd spam from Dovecot logs/LogWatch report

Chkservd adds lines like this to the Dovecot logs every 5 minutes, as checks to make sure it is up:

1. dovecot: imap(__cpanel__service__auth__imap__LONG_STRING_OF_ALPHANUMERICS_): Logged out in=11, out=434, bytes=11/434: 1 Time(s)

This adds a lot of spam to the logs and to the nightly Logwatch report, which is a bad thing if it makes people skip reading those reports. While one can edit /etc/logwatch/conf/ignore.conf so that it will ignore these entries, it would be much easier if this was an option in WHM's Dovecot or Logwatch configuration, since it is something that will pretty much affect every sysadmin. So either an option not to log those connections entirely (less optimal), or an option to suppress them from nightly Logwatch emails (better).