freshcutoff(): Return datetime

web.py/psycopg2/sqlite will handle the conversion itself, no need to swap
to seconds.
Warning that we're not sanitising all input.
updatefeed(): Test for existence

https://pythonhosted.org/feedparser/basic-existence.html ftw
updatefeed(): Return updated article_id's
updatefeed(): Better feed handling

Conversion to content/excerpt of ttrss api didn't work too well before.
This should stop the doubling up of content shown.
getArticle(): Provide feed data in rows to article()