Sort comments HTTP API responses by created_at, ascending
Change mentions of 'page' to 'entry' (as related to comments)
Mask repository exceptions for nonexisting keys with ResourceNotFound
Use md5 as key for comment collections tied to a URL
Repository::JsonSerializer raises Errno::ENOENT for nonexistent keys
Use strings as keys for Comment::Member attributes
Buffer member attributes, not members instances in Comment::Collection
Use sets to initialize collection keys in Repository::Memory
Add rake test task
Clean up left-over commented code bits