Improve express transfer to reduce site downtime.

As a web-host, we would like to improve how an express transfer to a new cPanel server is handled to reduce the downtime for the account’s website and e-mail addresses.

Currently when you transfer an account with the express transfer option, DNS records are updated to the new server IP before syncing the user’s homedir. We would like the homedir to be synced before changing the DNS records to reduce websites and e-mail accounts' downtime.