[SQL] Fix tiny/small ints from HiveMetastore.

Author: Michael Armbrust <michael@databricks.com>

Closes #797 from marmbrus/smallInt and squashes the following commits:

2db9dae [Michael Armbrust] Fix tiny/small ints from HiveMetastore.

(cherry picked from commit a4aafe5f9fb191533400caeafddf04986492c95f)
Signed-off-by: Reynold Xin <rxin@apache.org>