Add ability to enable SimplePie cache
Add a tiny graph for history log

- move zepto to the top (it's okay it's a backend !)
- integrate Morris to add a tiny modification to be usable for Zepto (instead of jQuery)
Add RSS/Atom formatter

- update deeps (sf 2.3.1)
- add rss & atom formatter (configurable per feed)
- rename `type_parser` to `parser`