Plugin [Andy] Duplicate account check 2.2

Fixed issue with Exclude usernames in options.

Fixed issue with checking deleted accounts.

Duplicate account check v2.0 changes:
Updated code used to get IP address.

Duplicate account check v1.9 changes:
Fixed issue dealing with intermittent duplicate entry error.

Duplicate account check v1.8 changes:
Corrected issue with Exclude usernames in the Options page.

Duplicate account check v1.7 changes:
Fixed issue where deleted accounts would still show as duplicate.

Duplicate account check v1.6 changes:
Now using finder for performing database queries.

Duplicate account check v1.5 changes:
Updated setup to use schema manager.

Duplicate account check v1.4 changes:
Cron entry now runs every 4 hours.