= New Features

* A timestamp_public plugin has been added for serving static files
  with paths that change based on the modification timestamp of the
  file.  By using a new path, cached versions of the file will not
  be used, fixing staleness issues.  Example:

    plugin :timestamp_public

    route do |r|
      # serves requests for /static/\d+/.*
      r.timestamp_public

      # /static/1234567890/path/to/file
      timestamp_path("path/to/file")
    end

= Other Improvements

* When using the assets plugin :timestamp_paths option, the
  timestamps now include microseconds, to make cache poisoning more
  difficult.
