Implement 99770 website.
Add index link at little title.
Add source code link in footer.
Implement error page.
Use macro of jinja2 to implement footer.
Merge branch 'feature/refine_UI' into develop
Add runtime.txt for heroku
Add content in README.md
Add the link of readme in the footer.

The outsite link is opened in new window.
Merge branch 'feature/readme' into develop
Add cache using session to speed up 8comic.
Implement CoimicSiteParser.
Change the code structure.
Merge branch 'feature/fasten_8comic' into develop
Merge branch 'release/0.5'