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.
I think it’d better to keep the constructor default (SQLAlchemy provides a default constructor which takes all column values by the same keywords) and rather define a new class method to fill columns from an item.