title: null in kafka streams need to be removed
body: <p>Just removing <code>--property print.key=true</code> this on my kafka-cosole-consumer command works for not displaying null on console....but the thing is it is not just for the display purpose i am using....my outputs from kafka streams need to go directly to the stream reactor,  then from there to influxdb.... my stream reactor will accept </p>
  
  <pre><code>{"timestamp":"2017-10-04T10:43:56.614451246+05:30","namespace":"/intel/psutil/load/load1","data":0.42,"unit":"Load/1M","version":0,"last_advertised_time":"2017-10-04T10:43:56.669248345+05:30"}
  {"timestamp":"2017-10-04T10:43:56.61445546+05:30","namespace":"/intel/psutil/load/load5","data":0.44,"unit":"Load/5M","version":0,"last_advertised_time":"2017-10-04T10:43:56.669251145+05:30"}
  </code></pre>
  
  <p>only this much.....it cannot accept </p>
  
  <pre><code>null    {"timestamp":"2017-12-05T13:52:43.560588466+05:30","namespace":"/intel/procfs/meminfo/active_anon","data":4183900160,"unit":"","tags":{"plugin_running_on":"AELAB110"},"version":4,"last_advertised_time":"2017-12-05T13:52:43.560658038+05:30"}
  null    {"timestamp":"2017-12-05T13:52:43.560618652+05:30","namespace":"/intel/procfs/meminfo/mem_free","data":49385746432,"unit":"","tags":{"plugin_running_on":"AELAB110"},"version":4,"last_advertised_time":"2017-12-05T13:52:43.560660098+05:30"}
  </code></pre>
  
  <p>so what can be the solution for this? plzz help me</p>