added irt bin compatibility with rails 3.1

bin/irt

@@ -96,8 +96,10 @@ cmd_format = if File.exists?('./config/environment.rb') && !options[:no_rails]
                      end
                    end
                  end
+                 rails_version = gemfile.match(/\bgem\b.+\brails\b.+3\.0\.\d/) ? '=3.0.*' : '>=3.1.*'
                  'rails c %s %s %s'
                elsif File.exists?('./script/console')
+                 rails_version = '2.*'
                  'ruby script/console --irb="irt_rails2 %2$s" %1$s %3$s'
                end
              else
@@ -107,6 +109,11 @@ cmd_format = if File.exists?('./config/environment.rb') && !options[:no_rails]
 ENV['IRT_INTERACTIVE_EOF'] = options[:interactive_eof].inspect if options[:interactive_eof]
 
 files.each do |file|
-  ENV['IRT_COMMAND'] = sprintf cmd_format, options[:irb_options], file, options[:rails_env]
+  ENV['IRT_COMMAND'] = case rails_version
+                       when '2.*', '=3.0.*'
+                         sprintf cmd_format, options[:irb_options], file, options[:rails_env]
+                       when '>=3.1.*'
+                         sprintf cmd_format, options[:rails_env], options[:irb_options], file
+                       end
   exit(1) unless system ENV['IRT_COMMAND']
 end