Updated spark-perf for running streaming tests

Added directory streaming-tests.
Updated config.py.template and run script to run streaming tests.

The run-tests() function in the run script needed to be changed so the output of streaming tests can be treated differently from the output of spark and shark tests (i.e., generation of statistics from multiple trials). I think this generation of statistics should be done in the TestRunner code rather than the run script, to keep the run script as generic as possible.