CA-127510: Reworked the logic of differentiating between tasks started by this instance
of XenCenter and tasks started from outside and cancelling the former when exiting
or disconnecting from the pool.

Signed-off-by: Konstantina Chremmou <konstantina.chremmou@citrix.com>
CA-127510: Refactoring as per code review.

Signed-off-by: Konstantina Chremmou <konstantina.chremmou@citrix.com>
Merge pull request #21 from kc284/master

CA-127510: Reworked the logic of differentiating between tasks started b...