Prepare align by adding `label` to table and crawl entities based on `ontology class`.

I added labels in order to align graphs easier.
`tvtropes` uses name as plain text in English, so I decided to use English label.

In addition, I started to crawl entities which are belong to `ontology class`, such as `Artist`, `Film` ... and so on.
is there any methods?, IntegrityError occurs when session inserts duplicated value, so i just updated timestamp `last_crawled`.