'Cloudsearch documents don\'t update unless the sent "version" field
is higher than the one currently indexed. As our documents don\'t have
"versions" and could in theory be updated multiple times in one second,
for now, use "tenths of a second since 12:00:00.00 1/1/2012" as the
"version" - this will last approximately 13 years until bumping up against
the version max of 2^32 for cloudsearch docs'

def _version_tenths(self):

    return (int((time.time() * 10)) - self._version_offset)
