Stop config-manager as first bundle when shutting down container.

If config-manager is stopped after a configured module's bundle has been stopped, config-manager will be unable to cleanly
close other instances, so it needs to be stopped as first bundle.
GlobalEventExecutorModule (netty-global-event-executor) is singleton, enforce it in only allowing one instance
called 'singleton'.
Make shutdown grace period smaller in order to close netty threads sooner that shutdown issues System.exit(1).

Change-Id: I042c606a5bedc49492784dcb0a5ad4dcbdcb0939
Signed-off-by: Tomas Olvecky <tolvecky@cisco.com>