Resync command improvements
Summary: Note that now the command requires LDAP/IMAP credentials available to it.
Test Plan: ./phpunit tests/Feature/Console/User/ResyncTest.php
Reviewers: #hkccp_developers, mollekopf
Reviewed By: #hkccp_developers, mollekopf
Subscribers: #hkccp_developers
Differential Revision: https://git.kolab.org/D4552