attempted to pull our Post.url_id method

but failed for some reason. just going to leave this here for now.
linting a bit
add initial support for tweets/tweet-length links

Now from the command line you can run:
`bin/omnivore links --tweets --all`, e.g.
and it will print out all the tweet length links it knows about. This
might be a lot. I need to add the option to {en,dis}able bit.ly in order
for this to not get super overwhelming in terms of bit.ly rate limiting
  and network traffic.