Personalization: Add better logging in the export feed process.

Description

There should be info-level logging for successful exports and warning/error-level logging for failed exports.

The scheduled job log should mention how many blobs are in the DB. Something like:
"Created X catalog feeds. There are now Y feeds awaiting export.

If there are more feeds awaiting export than were created by the latest job execution it indicates that earlier exports have not been successful.