Test alfa sensitive detector

In the branch, I tested the class called ALFA_SensitiveDetector in the package ForwardDetectors/ALFA/ALFA_G4_SD. Here is what I did about the package.

1. I put my test code ALFA_SensitiveDetector_gtest.cxx in the test folder. And it is for testing the class ALFA_SensitiveDetector.
2. I created the jobOption file optionForTest.txt, which is placed in the share folder.
3. In oder to add my test classes as friends of the tested classes, I add several lines for that.
4. Of course, I add some lines in the CMakeLists.txt for compiling my test code, using google test frame work, and so on.
5. I create 3 files and put them into the folder Simulation/G4Atlas/G4AtlasTools/G4AtlasTools. The 1st file is DerivedG4SensitiveDetectorTestSetting.h, where I define a function for setting G4-objects to G4Step object. The 2nd file is G4MyPhysicalVolume.h, where I define a class called G4MyPhysicalVolume that is derived from G4VPhysicalVolume. The 3rd file is G4MyProcess.h, where I define a class called G4MyProcess that is derived from G4VProcess.
6. It is worth mentioning that I use different TEST_F to test different member functions of the tested class.