Link to attachment should return latest attachment (#7510).
Underscores are allowed in project identifiers (#9225).
Bundle only the required database gems and adds sqlserver support (#12713).
Attachment name is added in the generated link.
Use helper.
Use named route with attachment filename for inline images.
Adds a named route for thumbnails and use route helper in #thumbnail_tag.
Add named routes for attachments and use route helpers in #link_to_attachment.
