Make possible to run Docker integration tests on PostgreSQL
Make possible to run Docker integration tests on PostgreSQL

Now it is possible to use PostgreSQL as the database when running the
integration tests on Docker by calling "run-docker.sh" with the
"--database pgsql" option.

It is not possible to wait for the PostgreSQL server to be ready using
curl like it was done for MySQL; when sending a HTTP request to the
PostgreSQL port the server sends an empty response, which curl sees as
an error. However, as Bash supports testing a connection with a remote
TCP socket, and this approach is valid for both MySQL and PostgreSQL
servers, the curl call was replaced with this Bash construct.

The default PostgreSQL database image is "postgres:10", the same
currently used when running the tests on Drone; a different one can be
specified with the "--database-image IMAGE_NAME" option.

Signed-off-by: Daniel Calviño Sánchez <bd7629e975cc0e00ea7cda4ab6a120f2ee42ac1b@gmail.com>

nextcloud/spreed,nextcloud/spreed,nextcloud/spreed