If the option is specified, the utility will pipe the test stdout/stderr
to separate files and dump them at the end.
BUG=8585
TEST=./bin/cros_run_parallel_vm_tests suite_Smoke suite_Smoke --order_output
Change-Id: I6c4fcb02456441b4e4fc3f1717cdb5d607d733b9
Review URL: http://codereview.chromium.org/4422001