Fixed streaming examples docs to use run-example instead of spark-submit

Pretty self-explanatory

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #722 from tdas/example-fix and squashes the following commits:

7839979 [Tathagata Das] Minor changes.
0673441 [Tathagata Das] Fixed java docs of java streaming example
e687123 [Tathagata Das] Fixed scala style errors.
9b8d112 [Tathagata Das] Fixed streaming examples docs to use run-example instead of spark-submit.