Updated vtkFileSystemUtilities and vtkGitFunctions

- vtkFileSystemUtilities
	- improved functions, working with hidden files and folders

- vtkGitFunctions
	- return values updated
	- vtkInitializeGit : log file not yet implemented

- vtkConstants
	-  updated list of return values (to be moved ?)

- Tester modules uncommented as code is now transparent.

- Added third-party module ShellAndWait from cpearson
	- removes the need of waiting for one second when executing Shell
	  commands