Fix bug where we were creating multple instances of various items in the settings table.

NOTE: If you're running sd-utility.php before v0.24 then execute the following in MySQL:

delete from settings where value in("mythfilldatabaseLastRunStart","mythfilldatabaseLastRunEnd","mythfilldatabaseLastRunStatus","MythFillSuggestedRunTime","MythFillSuggestedRunTime","MythFillSuggestedRunTime");