Added Update method to report on dbus

- Update method, updates timestamp and readings

Tested:
  - Added new unit tests covering update method
  - All existing unit tests are passing

Change-Id: I6b3829126d9060dbaf436cbf8e6917294dc03134
Signed-off-by: Krzysztof Grobelny <krzysztof.grobelny@intel.com>
diff --git a/tests/src/test_report_manager.cpp b/tests/src/test_report_manager.cpp
index 482434c..813fa19 100644
--- a/tests/src/test_report_manager.cpp
+++ b/tests/src/test_report_manager.cpp
@@ -54,8 +54,7 @@
             params.emitReadingUpdate(), params.logToMetricReportCollection(),
             static_cast<uint64_t>(params.interval().count()),
             params.readingParameters());
-        return DbusEnvironment::waitForFuture(addReportPromise.get_future())
-            .value_or(std::pair<boost::system::error_code, std::string>{});
+        return DbusEnvironment::waitForFuture(addReportPromise.get_future());
     }
 
     template <class T>
@@ -71,8 +70,7 @@
                 propertyPromise.set_value(T{});
             },
             [&propertyPromise](T t) { propertyPromise.set_value(t); });
-        return DbusEnvironment::waitForFuture(propertyPromise.get_future())
-            .value_or(T{});
+        return DbusEnvironment::waitForFuture(propertyPromise.get_future());
     }
 };