Add json file for opnfv_yardstick_tc015.yaml

Add json file for opnfv_yardstick_tc015.yaml

File opnfv_yardstick_tc015.json show sample data of test case
opnfv_yardstick_tc015.yaml. Power for energy scenario,
single_score and parallel_score for Unixbench scenario,
mpstat_average.cpu.%usr for cpu_load scenario.
You may also select other parameters to see the data trends
during test case running.

JIRA: YARDSTICK-1624
Co-authored by: Roland Picard <roland.picard@orange.com>

Signed-off-by: sungn <sungn2@lenovo.com>
Change-Id: I2b9993ad1d330c5f90ca8b5afda4e1dc73e8b150