Parsing JSON on the Arduino
This is how I would write this loop:

for (JsonArrayIterator it = root.begin(); it != root.end(); ++it) 
{    
  JsonObject row = *it;    

  char*  sensor    = row["sensor"];  
  long   time      = row["time"];  
  double latitude  = row["data"][0];
  double longitude = row["data"][1];

  Serial.println(sensor);
  Serial.println(time);
  Serial.println(latitude, 6);
  Serial.println(longitude, 6);
}


And, if C++11 is available (which is not the case with Arduino IDE 1.0.5):

for (auto row : root) 
{    
  char*  sensor    = row["sensor"];  
  long   time      = row["time"];  
  double latitude  = row["data"][0];
  double longitude = row["data"][1];

  Serial.println(sensor);
  Serial.println(time);
  Serial.println(latitude, 6);
  Serial.println(longitude, 6);
}