Lasts commits from vrolland

GridAccess interface :
	- add function to clean directory
	- Optimization of remove outpudate function
 
dirac-glast-pipeline-get-logfile :
	- Bug Fix
	- Optimization
  
dirac-glast-softwaretag-cli.py :
	- add function do_preinstall
	- add function do_installonsite
	
InstallSoftware.py :
	- Installation script on site 
	- Tag Registration