Implemented sensor class

Sensor class was introduced, it monitors
xyz.openbmc_project.Sensor.Value, for change and notifies all
listeners.

Tested:
  - Unit tested with service stub that provides dbus interface
    xyz.openbmc_project.Sensor.Value
  - All changes are delivered to listeners
  - All other unit tests are passing

Change-Id: I8c9d58cc986c1fe2a4d2386815d559814016efa6
Signed-off-by: Krzysztof Grobelny <krzysztof.grobelny@intel.com>
diff --git a/tests/src/main.cpp b/tests/src/main.cpp
new file mode 100644
index 0000000..6e29319
--- /dev/null
+++ b/tests/src/main.cpp
@@ -0,0 +1,16 @@
+#include "dbus_environment.hpp"
+
+#include <gmock/gmock.h>
+
+int main(int argc, char** argv)
+{
+    auto env = new DbusEnvironment;
+
+    testing::InitGoogleTest(&argc, argv);
+    testing::AddGlobalTestEnvironment(env);
+    auto ret = RUN_ALL_TESTS();
+
+    env->teardown();
+
+    return ret;
+}