Issue #10: give enough timeout that the Cursor in process_new_twits can run
  to completion regardless of how far behind it got, assuming the current
  15 requests in 15 minutes API rate limit.  A brutal approach (there's a
  tweepy fork with more advanced techniques) but this only occurs rarely,
  during recovery from various non-twitter outages usually.
display_rate_limit to allow easier debugging of issue #10; also *use*
the limit and don't bother failing on an interface we know we can't
use (so favorites and mentions continue to progress even when home
isn't able to progress, though the previous API retry_delay changes
should also avoid that case.)