tmf: Add asynchronous way of broadcasting signals

tmf: Add asynchronous way of broadcasting signals

For that the signal manager queues signals and executes them in order
of arrival in a separate thread.

Unit tests were added for the signal manager.

Change-Id: If3957bcdcc30dec3f25804586c6ee5aa10a102a1
Signed-off-by: Bernd Hufmann <Bernd.Hufmann@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/20590
Reviewed-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
IP-Clean: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Tested-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Tested-by: Hudson CI
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>