Added Periodic reportingType support to Report

When report interval expires report will collect readings from
metrics and update timestamp.

Tested:
  - Added new units tests covering added code
  - All existing unit tests are passing

Change-Id: I7f23ca05d77efb0f18d2c0d0f138c524ffb4f6af
Signed-off-by: Krzysztof Grobelny <krzysztof.grobelny@intel.com>
diff --git a/tests/meson.build b/tests/meson.build
index fbee253..73846f6 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -23,6 +23,7 @@
     executable(
         'telemetry-ut',
         [
+            '../src/metric.cpp',
             '../src/persistent_json_storage.cpp',
             '../src/report.cpp',
             '../src/report_factory.cpp',
@@ -33,6 +34,7 @@
             'src/main.cpp',
             'src/stubs/dbus_sensor_object.cpp',
             'src/test_detached_timer.cpp',
+            'src/test_metric.cpp',
             'src/test_persistent_json_storage.cpp',
             'src/test_report.cpp',
             'src/test_report_manager.cpp',