Pass fully qualified constants to #setsockopt

Fixes #396.

lib/capybara/webkit/connection.rb

@@ -113,7 +113,7 @@ module Capybara::Webkit
     def attempt_connect
       @socket = @socket_class.open("127.0.0.1", @port)
       if defined?(Socket::TCP_NODELAY)
-        @socket.setsockopt(:IPPROTO_TCP, :TCP_NODELAY, 1)
+        @socket.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, true)
       end
     rescue Errno::ECONNREFUSED
     end

spec/connection_spec.rb

@@ -38,7 +38,7 @@ describe Capybara::Webkit::Connection do
     socket = stub('socket')
     TCPSocket.stub(:open).and_return(socket)
     if defined?(Socket::TCP_NODELAY)
-      socket.should_receive(:setsockopt).with(:IPPROTO_TCP, :TCP_NODELAY, 1)
+      socket.should_receive(:setsockopt).with(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, true)
     else
       socket.should_not_receive(:setsockopt)
     end