Fix Rubocop errors

Author: lfidnl

lib/grape/util/sendfile_response.rb

@@ -3,7 +3,7 @@ module Util
     # Response should respond to to_path method
     # for using Rack::SendFile middleware
     class SendfileResponse < Rack::Response
-      def respond_to?(method_name, include_all=false)
+      def respond_to?(method_name, include_all = false)
         if method_name == :to_path
           @body.respond_to?(:to_path, include_all)
         else

spec/grape/integration/rack_sendfile_spec.rb

@@ -25,7 +25,7 @@
       double(:file_streamer, to_path: '/accel/mapping/some/path')
     end
 
-    it "contains Sendfile headers" do
+    it 'contains Sendfile headers' do
       headers = subject[1]
       expect(headers).to include('X-Accel-Redirect')
     end
@@ -36,7 +36,7 @@
       double(:file_streamer)
     end
 
-    it "not contains Sendfile headers" do
+    it 'not contains Sendfile headers' do
       headers = subject[1]
       expect(headers).to_not include('X-Accel-Redirect')
     end