Make sure updated_at dates change when relations do
Include modified date header

Also means this will respond to conditional gets via app
which will be faster than via nginx
Use consistent date time formatting in atom feed

Also use Z for timezone offset as it’s easier to read and might save a few chars
Filter index by date

Hidden option so only really going to be much use in the atom feed as most mortals probably can’t type a valid iso8601 date.
Fix spooky action at a distance failure

The touch of `response_set` added to `Certificate` changed the updated_at date.

Solved by sticking creation in a `Timecop.freeze` block
Merge pull request #957 from theodi/feature-recency-filter-feed

Filter atom feed by modified date
Prevent hidden datasets showing up to public users
Don’t show certificate pages either if not visible
parse iso8601 dates so that partial dates work

Ruby’s DateTime::iso8601 method doesn’t give reliable results when given partial dates
2014 will give you todays date but at 20:14
2014-03 will give you 2014-01-03 instead of 2014-03-01
If no results in search use now as modified date.
Only use response_set’s updated_at date so search and displayed results are consistent
Merge pull request #958 from theodi/bugfix-remove-removed-datasets

Hide removed datasets from prying eyes everywhere
Merge pull request #960 from theodi/bugfix-improve-date-filtering

improve date filtering
Document all of the search facilities
Report a certificate

send an email to certificate@theodi.org with their reasons
for reporting it and a contact email.
Merge pull request #961 from theodi/feature-report-certificates

Report problematic certificates
Documentation for certificate claiming
Make staging environment check explicit
Report airbrake environment as staging or production
Stop datasets#show exploding on unpublished certificates