Tempest instructions are outdated

[Pierre Riteau]

The instructions for running Tempest scenario tests, located in contrib/tempest/README.rst, are out of date. They result in the following error:

    /usr/bin/bash: tools/pretty_tox.sh: No such file or directory
    ERROR: InvocationError: '/usr/bin/bash tools/pretty_tox.sh (^tempest\\.(api|scenario|thirdparty|cli)\\.test_.*reservation) '

[Bertrand Souville (souville)]

I add the following to the tox.ini in my local environment (Tempest scenarios only):

[testenv:blazar]
envdir = .tox/tempest
sitepackages = {[tempestenv]sitepackages}
setenv = {[tempestenv]setenv}
deps = {[tempestenv]deps}
commands =
    find . -type f -name "*.pyc" -delete
    tempest run --serial --regex '(?:tempest\.scenario\.test_.*reservation.*)' {posargs}

See also https://github.com/openstack-infra/project-config/blob/master/jenkins/jobs/blazar.yaml

[Jason Anderson (jasonandersonatuchicago)]

@priteau has added some new instructions to an Etherpad which can serve as a useful guide until official docs are updated: https://etherpad.openstack.org/p/blazar-running-tempest