added unit tests for SiUnitFactory
implemented UnitNotDetectedException in Measurement
removed finished ToDo from Measurement
implemented UnitNotDetectedException in MeasurementDevice
added InvalidValueProvidedException
implemented InvalidUnitProvidedException in WeightUnit
implemented InvalidValueProvidedException in LengthUnit
removed finished ToDo from LengthUnit
implemented InvalidValueProvidedException in Measurement
implemented InvalidValueProvidedException in MeasurementDevice
updated UTestLengthUnit to fail more strict
updated UTestWeightUnitTest to fail more strictly
updated UTestMesurement to implement InvalidValueProvidedException
updated UTestMeasurementDevice to implement UnitNotDetectedException
updated UTestMeasurementDevice to implement InvalidV.ProvidedException
fixed some noob error catching errors in UTestMeasurementDevice