HOTFIX: Ignore streaming UI test

This is currently causing many builds to hang.

https://issues.apache.org/jira/browse/SPARK-1530

Author: Patrick Wendell <pwendell@gmail.com>

Closes #440 from pwendell/uitest-fix and squashes the following commits:

9a143dc [Patrick Wendell] Ignore streaming UI test
(cherry picked from commit 7863ecca35be9af1eca0dfe5fd8806c5dd710fd6)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>