Use classes to describe pieces of acme windows.

The following commits will make the feed list look like acme too. This
will remove a huge amount of CSS duplication.
Make the feed list page look like acme too.

Fixes #92
Use path.Base instead of hard coding the index.
Cleanup the feed list page data structures.
Change subscribe/unsubscribe to use a text area of URLs.

The unsubscribe check boxes were very ugly, and subscribing to
individual feeds is clumsy.

Fixes #105
Put the feed URL in the feed list win body.
Merge pull request #106 from eaburns/dev/acmestyle

Change the feed list to use the acme style.