Log Message:
Update ruby-rack-contrib to 1.4.0.

v1.4.0: Features, Features Everywhere, and not a bug to fix

There's a bumper crop of new features this month. Share and enjoy!

Deprecations

* Rack::AcceptFormat is slated for removal in rack-contrib 2.0.0 (due on or
  after 1 January, 2016. Using this middleware will now result in a
  deprecation warning being printed to stderr. If you use this middleware, now
  would be a good time to start doing things properly.

Features

* Rack::LazyConditionalGet: new middleware, by Mig. This middleware tracks
  when the last POST/PUT/DELETE request was made, and returns 304 responses to
  requests which include a Last-Modified entity request header which is
  greater than or equal to that time.

* Rack::StaticCache: You can now specify a custom "version" regex for your
  cache invalidation, if the default doesn't do it for you. Initial patch
  provided by Eric Boehs.

* Rack::Profiler: You can now run a single request through the profiler
  multiple times, by adding the profiler_runs query parameter to the
  URL. Patch provided by Bryce McDonnell.