[INTERNAL] fix for commit 1858e59360bee94010642e4152278263455f56eb

Fixed a deadlock that was causes by simply forgetting to remove the
synchronized keyword from the resumeHandle method.

This patch changing again synchronization by using a dedicated object to
signal the arrival of stop responses instead of using the StopManager
object itself.


Change-Id: I96c47a79499e93c1a27160e2d1d96479e5330fcf
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1446
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>