Remove obsolete golden images

[luizgrp]

It would be nice if the library could take care of removing obsolete golden images.

For example, when a function name is renamed, the task recordPaparazziDebug generates new golden images for the new function name, leaving the golden images for the previous function name in the folder, which are no longer in use.

[geoff-powell]

yes we added a cleanRecordPaparazzi{Variant} task to do this exact thing.