Add a timing listener that also prints the results

Instead of just recording them it can also be quite
useful (especially for debugging) to print the start
and stop timings as they occur.

Also adds an example that shows how this can be used
and an explanation of why it is useful to have this type
of capability.

Part of blueprint more-examples

Change-Id: Id2dc3f8dc9ac94e511470e39f499f325b33537ee
Merge "Add a timing listener that also prints the results"