Add upgrade task to fill in missing settings / convert relevant from config

Hi Tim

I think CRM_Core_BAO_Setting::updateSettingsFromMetaData();

is ready to be included in upgrade scripts / setup.sh -

The intent is that it can be run @ any time & it will sort out any missing settings - it compares set settings with all settings & fills in missing ones from config and / or defaults & unsets $config if not 'prefetch'.

(multisites will have currently lots of missing settings as they have been a bit hit & miss - esp in 4.1 upgrade).

Not sure where / how best to add it in...

Eileen