Absolute URLs for links appearing in feed

note that this changes the oft-used byline()

http://code.google.com/p/otwarchive/issues/detail?id=2954
Much-belated review /o\

I don't know if you're still around, @openendings, but if you are and still willing to work on this:

I would prefer if this was put on the same line as the text above. Also, given that we're nearing the translation stage, if this was turned into a translation string with interpolated variables, like so:
```ts("Part %{serial_index} of %{link_to_series}", serial_index: s.serial_works.where(work_id: work.id).select(:position).first.position, link_to_series: link_to(s.title, series_url(s)))```