[SPARK-7287] enabled fixed test

andrewor14 pwendell I reenabled the test. Let's see if it's fixed. I did also notice that `--jars` started to fail after this was ignored though in the JIRA. like [here](https://amplab.cs.berkeley.edu/jenkins/job/Spark-Master-SBT/AMPLAB_JENKINS_BUILD_PROFILE=hadoop2.0,label=centos/2238/consoleFull), you see that --jars fails for the same exact reason.

Has any change been made to Spark Submit recently? Did the test setup on Jenkins change? If we look into flaky tests last month, you wouldn't find this test among them.

Author: Burak Yavuz <brkyvz@gmail.com>

Closes #5826 from brkyvz/restart-test and squashes the following commits:

f509f68 [Burak Yavuz] enabled fixed test