Allow to run tests with PostgreSQL inside container
This patch introduces a new environment variable in order to allow running
tests with different database backend. This is useful particularly for running
tests inside container. With this change, it is possible run tests in following
combinations:
* Python 2 and SQLite
* Python 3 and SQLite
* Python 2 and PostgreSQL
* Python 3 and PostgreSQL
Package python-psycopg2 is installed in both Dockerfile-tests and
Dockerfile-tests-py3 in case of running tests with PostgreSQL.
A new script contrib/run-unittests.sh is added to make it easy to run tests. An
example:
contrib/run-unittests.sh --py3 --with-pgsql
that runs tests with Python 3 and PostgreSQL.
Signed-off-by: Chenxiong Qi <cqi@redhat.com>