Using subquery to avoid locking
Indexes for the most used queries
release 0.2.17
Removing old workers
proper index
release 0.2.18
removing worker zombies
RElease 0.2.19
Fixed LinkCrawlerValidator

Setting URL with 'response.effective_url'
Fixing review and page tests

The last_review_started_date was removed
Fixed Reviewer enqueue
Fixed review tests