Changing devstack environment vagrant box and
also rename the devstack VM to 'devstack'
from 'pg-tips'
Also fixing all the tests that were broken when
they were moved from tests/unit to tests/functional
with this review
https://review.openstack.org/#/c/400237/
Update devstack README with a section called
Development workflow for monasca-transform with
steps developers can take to develop and run
tests.
Change-Id: I11678148ba2bcb96eb3e2a522176683dc8bca30a