WIP - Changed combination among fetch, parse and save.

Details
- Currently fetching is independent and parsing and saving are
  combined. But an issue was found that fetching and parsing should be
  combined because parsing function is needed to distinguish the last
  page of wordbook in fetch_all_page function.

TODO
- Rewrite fetch_all_page function and test case so that it can fetch,
  parse and save.
- Delete integration test scenarios because they were already included
  in the other part.
- Delete parse_and_save function (already commented out)
- Delete the last part of set_fakeweb (already commented out)