SPARK-1607. HOTFIX: Fix syntax adapting Int result to Short

Sorry folks. This should make the change for SPARK-1607 compile again. Verified this time with the yarn build enabled.

Author: Sean Owen <sowen@cloudera.com>

Closes #556 from srowen/SPARK-1607.2 and squashes the following commits:

e3fe7a3 [Sean Owen] Fix syntax adapting Int result to Short