Functional tests have been moved to a separate tox
enviroment called functional, so running either py26
or py27 one will only trigger unit tests.
Scripts for prepairing and cleaning up Nailgun environments
have been factored out of run_tests.sh.
run_tests.sh is kept just compatibility reasons and will be
removed once FuelCI is updated.
DocImpact
Partial-bug: #1476808
Closes-bug: #1486030
Change-Id: I492ce5d1ed26a182cc6876594d4508088afd5411
224b490d7d