Review fixes for 'Created metric class'

- Changed metric to_json to dumpConfiguration returning LabeledTuple
- LabeledTuple can be created and assigned directly to json
- LabeledTuple can be readed from json using json.get<LabeledTuple>
- Added PrintTo for LabeledMetricParams, LabeledSensorParams
- Added helper method expectMake to ReportFactoryMock
- sensorPaths are serialized to tuple<service, path> instead of single
  field with service and path separated via ':'
- Changed configuration version from 1 to 2

Change-Id: I7c45fb584687172f88fd549a93329264793b0b8e
Signed-off-by: Krzysztof Grobelny <krzysztof.grobelny@intel.com>
diff --git a/src/metric.hpp b/src/metric.hpp
index 6e27446..39f525c 100644
--- a/src/metric.hpp
+++ b/src/metric.hpp
@@ -17,7 +17,7 @@
     const std::vector<MetricValue>& getReadings() const override;
     void sensorUpdated(interfaces::Sensor&, uint64_t) override;
     void sensorUpdated(interfaces::Sensor&, uint64_t, double value) override;
-    nlohmann::json to_json() const override;
+    LabeledMetricParameters dumpConfiguration() const override;
 
   private:
     MetricValue& findMetric(interfaces::Sensor&);