Add performance_tuning task

The task tunes up the Satellite 6 performance on both bare metal machine
and virtual machine according to the running_on_vm argument.
Merge pull request #58 from elyezer/performance-tuning

Add performance_tuning task
Increase poll subscribe retries

Automation matrix have increased and the poll subscribe is failing again
due to the concurrent subscription. Because this is better to increase
to a higher number to make sure all machines gets subscribed to the
poll.
Merge pull request #59 from elyezer/subscribe-retries

Increase poll subscribe retries