Ticket #48778 - PassSync installer overwrites "Notification Packages" value in registry instead of appending it
    
    Bug Description:
    During the installation of the PassSync, key "Notification Packages"
    in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\
    is owerwritten instead of being appended.
    
    Fix Description:
    Use MultiStringValue for updating the registry value:
    http://wixtoolset.org/documentation/manual/v3/xsd/wix/multistringvalue.html
    
    https://fedorahosted.org/389/ticket/48778
    
    Reviewed by: nhosoi@redhat.com