fix show table tree

Batch mode

* Fix TableResult#wait() timeout parameter
* Fix for batch queries with an empty result

execution_result.wait(self.wait_timeout_ms) does not finish
when SELECT query return empty results. Other queries either
return immediately or always return at least one row. Therefore,
we can call wait() on queries other than SELECT. In case of
SELECT queries, we can block on CloseableIterator<Row> returned
by collect() method.

Release 0.9.0