db engine created on worker process init
Handle some exceptions

IntegrityError, FlushError and MultipleResultsFound exception are now handled.
This commit is functional.
Fix line 139: from url to destination_url
Merge remote-tracking branch 'upstream/master' into sqlalchemy
More robust Entity
Add tvtropes Redirections
Revert "Add tvtropes Redirections"

This reverts commit ec9964c601e846cba101c046581a35b156b766a2.
Merge remote-tracking branch 'upstream/master' into sqlalchemy
Use requests for url fetch
Add requests to install_requires
Clarify column names in Relation

Alembic is not working in my environment, so migration is not yet created.
Add alembic migration
Conform PEP 8
Add TVTropes Redirection ORM
Crawler get redirection aliases
Fix indexindex when 'The' in name
Add tvtropes Redirection migration
Removed statistical parameters from crawl_link
Removed save_link, seeds goes to celery queue
Changed seeding message