Unread count.

+ Implemented a counter for unread feed entries. Works pretty well if
the publish date for the entries is handled properly in the feed (I'm
looking at you, Feber.se!).
+ Added functionality to see all feeds at the same time (sorted after
publish time).
+ Added functionality to remove all feeds.
* Moved web store stuff to own (static) class.
* Remove button is now next to the feed name.
* List of feeds is now a CellTable! How quaint!
* Minor UI tweaks.