[INTERNAL] fixed NPE due to race condition

The EditorManager is initialized after the session components are
initialized. As a result the ConsistencyWatchdogServer was already
calling getRemoteOpenEditors() which lead to a NPE because the
remoteEditorManager variable was still null.

Change-Id: I9ca050090069cb6d935bb2c7fc46df616804ee40
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1855
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>