Add glance notifications tests for ceilometer

Added ceilometer test for measurements:
image.update, image.upload, image.delete, image.download, image.serve

measurements: image, image.size are not added to tests because they 
have status 'both', these measurements are pollster and notification
ones at the same time.

Partially implements: blueprint add-basic-ceilometer-tests

Change-Id: Id049b6cb8ab3092c50f35894cf5a6bda7ff04617
Merge "Add glance notifications tests for ceilometer"