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This makes use of the new environment field that can be
added to the database declaration and is then used to
select the runtime environment in place of the database
search done until now.

This avoids accidental writes in the container that
will be lost anyway.

This allows to have a cleaner content and a dedicated place for
error related tests.

Fixes #60

This avoids to depend on other tests running before to have all
algorithms built.

The DOCKER_TEST_DEBUG environment variable can be used to
enable executor debug mode.

This reverts commit a6ab4867, reversing
changes made to 5c7900bc.

Bogus test phase.

This by default disable tests that requires the capabilities
to create new docker network on the fly.

This assumes that the environment are setup using conda.