Refactor code to give state transfering making more sense.
Support getting related movies from recommendations.
Support querying movie title and publish year from HTML.
Add methods to parse celebrity IDs.
Allow creating SQLite database to save data.
Support saving movie data into database.

This is a big change to enable we save data into sqlite3 database. It
provides the features below:

1. A command line interface to execute spider.
2. Save data to database.

Pending work items:
1. Some pages has wrong title: http://movie.douban.com/subject/1421770/
2. Solve the /search/string pages from celebrities.
3. Load history from data on new fetch.