Improve sudooption docs, make the option multi-value
    
    I don't know why this wasn't always multi-value but if one wanted
    to set multiple options they needed to call add-option multiple
    times. The LDAP attribute is already multi-value.
    
    This shouldn't cause API issues as it understood the attribute as
    multi-value just didn't expose it. Client output on the CLI will
    look a bit different:
    
    Added option "('one', 'two')" to Sudo Rule "test"
    
    or
    
    Added option "(u'one', u'Two')" to Sudo Rule "test"
    
    instead of with this change:
    
    Added option "one,two" to Sudo Rule "test"
    
    Removing an option works in a similar way.
    
    The value is normalized on the client side in order to ensure that
    the option value is always a tuple.
    
    https://pagure.io/freeipa/issue/2278
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>