mock out the Zend_Mail_Transport object in unit tests (fixes #3444, BP from #3443)
(cherry picked from commit 2d73654a5ed2755c2cfe52a8be9e10e49e95eb1a)
use opZendMailTransportMock for CommunityMemberTable::processJoinConfirm() tests (fixes #3444, BP from #3443)
(cherry picked from commit b9a0894299d19644281bf3eca2a37ec572371b41)