Make an error message more readable when a telnet-style RPC fails.
Make an error message more readable when a telnet-style RPC fails.

This is less readable and helpful:
  Unexpected exception caught while serving [Ljava.lang.String;@a5c087f
than this:
  Unexpected exception caught while serving ["some", "bad", "request"]

Change-Id: I90a6c3aa6e7fc3963416cd19609469796cb4dc65

eswdd/opentsdb,OpenTSDB/opentsdb,eswdd/opentsdb,alienth/opentsdb,johann8384/opentsdb,MadDogTechnology/opentsdb,OpenTSDB/opentsdb,kidaa/opentsdb,MadDogTechnology/opentsdb,andyflury/opentsdb,MadDogTechnology/opentsdb,sidhhu/opentsdb,kidaa/opentsdb,andyflury/opentsdb,ShefronYudy/opentsdb,alienth/opentsdb,sidhhu/opentsdb,johann8384/opentsdb,OpenTSDB/opentsdb,ShefronYudy/opentsdb