Allow to used mixed case for sysrestore
    
    This commit allows to use mixed case of keys for sysrestore, before this
    commit all keys were saved in lowercase what prevents to accesing them.
    
    Original usage of mixed case for sysretore key in opendssecinstance had
    to be changed to lowercase to prevent issues on already installed
    systems.
    
    https://fedorahosted.org/freeipa/ticket/5574
    
    Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>