Don't use the Accept request header when generating ETags for images which contain an extension in the URI. Fixes #254
Updated ChangeLog
Added more behat tests
Added a section on cache headers
Added an event listener that will handle ETag's for all resources supporting this
Added some more scenarios to the etags feature
Enable the new listener
Removed code related to the ETag header as this is now handled by an event listener
Updated ChangeLog
Removed comment
Merge pull request #254 from christeredvartsen/issue-254

Improve handling of ETag's