Added python-dev even though it's picked up
by other projects already, just to be explicit.
Also added libpq-dev, this way users can just
run "sudo pip install -r test-requirements.txt"
and perform everything in run_tests.sh without the
need for venv.
Change-Id: I3953032ac40ef78fc6f67d77539e13539fbbb2ac
4b60089874