Added telemetry in the preview processor
(Paris2013) Use Date.UTC so that the date is not created with a local GMT offset.
Simple image preview names
Added unit tests for filenames
Setting preview status to ignored for ignored items
(Paris2013) Call the callback if there is an error generating
Better PDF parsing + documentviewer compliancy

Conflicts:

	node_modules/oae-content/lib/util.js
Lower-casing 'IO' in requires statement
Temporarily stringifying the previews object.

Once the activities PR lands this can be removed.