This adds a wrapper class that detects if a callable object in any of
the descendent objects raises an Exception. If so, then it retries that
exception.
This is to attempt to make the zaza tests a little more robust in the
face of small network failures or strange restarts. This is a test, and
robust logging a reporting should be used to determine whether it is
covering up actual bugs rather than CI system issues.
Related Bug: (zot repo)#348
45146b6c45