[SPARK-2392] Executors should not start their own HTTP servers

Executors currently start their own unused HTTP file servers. This is because we use the same SparkEnv class for both executors and drivers, and we do not distinguish this case.

In the longer term, we should separate out SparkEnv for the driver and SparkEnv for the executors.

Author: Andrew Or <andrewor14@gmail.com>

Closes #1335 from andrewor14/executor-http-server and squashes the following commits:

46ef263 [Andrew Or] Start HTTP server only on the driver
[SPARK-2413] Upgrade junit_xml_listener to 0.5.1

which fixes the following issues

1) fix the class name to be fully qualified classpath
2) make sure the the reporting time is in second not in miliseond, which causing JUnit HTML to report incorrect number
3) make sure the duration of the tests are accumulative.

Author: DB Tsai <dbtsai@alpinenow.com>

Closes #1333 from dbtsai/dbtsai-junit and squashes the following commits:

bbeac4b [DB Tsai] Upgrade junit_xml_listener to 0.5.1 which fixes the following issues