tests: use batch queue on Beagle2

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: lower the actor-to-node ratio

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: document the configuration file

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
decision_maker: improve timeout selection code

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>