Major update

Major updates to layout and styles. The extension popup window is now
less cluttered.

There is now an 'Add Feed' page. The button in the upper left opens this
page to display the old 'Add Feed' form. Now in addition to this form,
the extension will also detect and display feeds available in the
currently selected tab. You can click these feeds to add the URL to the
'Add Feed' form.

Also when you navigate to a web page or open a tab that contains an
available feed, the extension icon will show a little + in the upper
right corner.