thorium: add helper to unpack 2 int values

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: fix bug in function that sends 2 int values

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: ACTION_ENABLE_MESSAGE_CACHE needs request and reply actions

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