enabling BloglistDeferredPurgeJob, BlogTask, CreatePdfThumbnailsJob to run under the new job queue system

(cherry picked from commit 162dbc61d2737f3e3b897bea71b1f175e9555237)
change new task system to instantiate titles like hte old job system
Merge pull request #3612 from Wikia/jobqueue-enable_tasks

enabling some tasks