Flush all logging immediately

... so that scripts invoking beanstalkify can choose to merge the info.

For example in Node.js:
beanstalkify = exec "beanstalkify -k .....", (err, stdout, stderr) ->
   grunt.fail.fatal(err) if err
   done()
 beanstalkify.stdout.on 'data', (data) ->
   console.log "[beanstalkify] #{data}"