alter restore checks from folder-based check to database-based checks

domainexistcheck() - checks psa db instead of /var/www/vhosts folder
restore() - does not store remote mysql password as a variable any longer, checks psa database for restored domains instead of /var/www/vhosts
restoreprogress() - while unused, no longer uses above variable
syncclients() - now checks psa database for $restoredtest instead of grepping ls of /var/www/vhosts
syncdomains() - fixes as per syncclients()