Do not return response body for HEAD requests

"The HEAD method is identical to GET except that the server MUST NOT
return a message-body in the response."

http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.4

Signed-off-by: Stephen Celis <[email protected]>

Author: stephencelis

lib/grape/endpoint.rb

@@ -296,6 +296,7 @@ def run(env)
     def build_middleware
       b = Rack::Builder.new
 
+      b.use Rack::Head
       b.use Grape::Middleware::Error,
         :default_status => settings[:default_error_status] || 403,
         :rescue_all => settings[:rescue_all],

spec/grape/api_spec.rb

@@ -284,7 +284,7 @@ def app; subject end
           verb
         end
         send(verb, '/example')
-        last_response.body.should eql verb
+        last_response.body.should eql verb == 'head' ? '' : verb
         # Call it with a method other than the properly constrained one.
         send(verbs[(verbs.index(verb) + 1) % verbs.size], '/example')
         last_response.status.should eql 404

spec/grape/endpoint_spec.rb

@@ -410,7 +410,7 @@ def memoized
         end
         send(verb, '/example/and/some/more')
         last_response.status.should eql (verb == "post" ? 201 : 200)
-        last_response.body.should eql verb
+        last_response.body.should eql verb == 'head' ? '' : verb
       end
     end
   end