pass through a 500 error
Add in working buckets
Write out in-date buckets
PEPPY
Add integration tests for read/status

- update last time updated migration to ignore a list of rarely modified buckets
- ignore bucket recency when max_age_expected is `None`
Merge branch 'master' into more_log_response_messages

* master:
  Pep8...as always
  Add migration
  Test range of quarters
  Test for end of quarter
  Validate quarter starts
  Starts for each quarter
  Hardcode quarter start to October
  Change replicate dirs to point at new dev vm
Merge pull request #181 from alphagov/more_log_response_messages

Check bucket health separate to _status endpoint