Re-added: Courier as IMAP/POP3 server alternative (Debian Jessie)

    [feedquote='i-MSCP Github (stable) (nuxwin)','https://github.com/i-MSCP/imscp/commit/3090c286e65618f9d6547298e6330a771f9bc76a']

    Code
    1. Re-added: Courier as IMAP/POP3 server alternative (Debian Jessie)
    2. Fixed: Bind9 cannot start if the resolvconf package is not configured yet (Debian Squeeze)
    3. Fixed: Installer hangs while packages installation (Debian Jessie)

    [/feedquote]