Fix EntityManagementSupport race for changeListener

- Fixes race where effector called post-exec listener concurrent
  with app.stop(), which unmanaged the app.
  Caused exception, and thus test's tearDown to fail.
Fix thread-safety in NonDeploymentManagementContext
Merge pull request #658 from aledsage/cherrypick/EntityManagementSupport-race

Fix EntityManagementSupport race for changeListener (0.5 branch)