python: add support for lockspace events
    
    Add support for sending events to other hosts and listening for
    lockspace events.
    
    I added thin wrappers for sanlock_reg_event, sanlock_get_event,
    sanlock_end_event, and sanlock_set_event.
    
    Where sanlock C API has unused arguments, the Python bindings do not use
    them, since we can add them later as optional arguments in a backward
    compatible manner. This ensures that new code depending on this argument
    will fail when working with a version that does not provide it.
    
    sanlock_get_event returns one event per call. The Python version is
    easier to use, returning list of events in one call, similar to
    get_hosts.
    
    Signed-off-by: Nir Soffer <nsoffer@redhat.com>