Add test for Cyrus imap proxy bug
Summary:
Add test for Cyrus imap proxy bug
Update rcube_imap_generic from Roundcube master. It includes fixed error handling on FETCH.
Test Plan: ./phpunit
Reviewers: #hkccp_developers, mollekopf
Reviewed By: #hkccp_developers, mollekopf
Subscribers: #hkccp_developers
Differential Revision: https://git.kolab.org/D4637