Plack::Middleware to override REST methods via POST

 Plack::Middleware::MethodOverride provides a workaround for writing RESTful
 Plack applications that also support web browsers. Using a header named
 X-HTTP-Method-Override or a form action parameter named x-tunneled-method,
 the REQUEST_METHOD key of the Plack environment hash will be replaced with
 the specified value, allowing a POST request to be used in place of any the
 other HTTP methods.