Expand test framework and test cases (#685)

* Fix comment

* Ekf wrapper for testing

Add utility function for accessing information in the ekf object

* Add step function for Gps sensor

* Add RangeFinder and Flow to simulated sensors

* Add first fusion logic tests

* Add units to function name

* Use EXPECT_TRUE

* Adding missing qualifiers

* Improve EXPECT_ calls

* Improve naming

test/sensor_simulator/mag.cpp

@@ -26,4 +26,4 @@ void Mag::setData(const Vector3f& mag)
 }
 
 } // namespace sensor
-} // namespace sensor_simulator::sensor
+} // namespace sensor_simulator