Ability to run OSTF against user defined deployment

In order to run certain OSTF test multiple time you
need to set DEPLOYMENT_NAME environment variable.
Other variables should be set same way as in ordinary
system tests run.

Change-Id: I6cf70270acb2fd9deca1efd7eb6caad36b77daf8
Merge "Ability to run OSTF against user defined deployment" into stable/4.1