Delete commented codes from test_vmtasks.py

There are some commented codes in tests/benchmark/scenarios/vm/test_vmtasks.py,
and
https://github.com/stackforge/rally/blob/master/tests/benchmark/scenarios/vm/test_vmtasks.py#L85
is longer than 80. This patch removes these useless lines.

Change-Id: I7ad67742f19c2009589d8e9d7b171a3c685c53ee
Asynchronous result yielding for scenario runners

Benchmark engine spawns a consumer thread, which asynchronously handles results
for each scenario run. Current consumer implementation just collects all
results and stores them as 'raw' to save integrity.

Scenario runners have to call _send_result method for every single result
instead of collecting a list of results.

Change-Id: Icbff8b2470af3b3ced6bb55573b5842726177b70
Merge "Asynchronous result yielding for scenario runners"
Whole scenario time measurement

Change-Id: I2708a5f915d5b13948f50dfad26b2463b9d5249b
Updated rally gate scenarios

Change-Id: I021e4be45cf3e9d92c9e099cec63ae844831c995