Implement HwmonTemperatureSensor, add serialization

app/include/HwmonTemperatureSensor.h

@@ -1,11 +1,18 @@
 #ifndef HWMONTEMPERATURESENSOR_H_
 #define HWMONTEMPERATURESENSOR_H_
 
+#include <sensors/sensors.h>
+
 #include <TemperatureSensor.h>
 
 class HwmonTemperatureSensor : public TemperatureSensor {
 public:
   int getTemperature() override;
+  std::string toJson() override;
+
+private:
+  sensors_chip_name mChipName;
+  sensors_subfeature mSubFeature;
 };
 
 #endif // HWMONTEMPERATURESENSOR_H_

app/include/TemperatureSensor.h

@@ -1,9 +1,12 @@
 #ifndef TEMPERATURESENSOR_H_
 #define TEMPERATURESENSOR_H_
 
+#include <iostream>
+
 class TemperatureSensor {
 public:
     virtual int getTemperature() = 0;
+    virtual std::string toJson() = 0;
 };
 
 #endif // TEMPERATURESENSOR_H_