CA-108676:  Put the Heartbeat and event.next sessions on their own ConnectionGroups.

Also make sure that the MeddlingAction's cancel session gets disposed.

Signed-off-by: Mihaela Stoica <mihaela.stoica@citrix.com>
Merge pull request #101 from MihaelaStoica/CA-108676

CA-108676:  Put the Heartbeat and event.next sessions on their own ConnectionGroups