Allow to externalize the configuration of DEPLOYMENT_EXTENSIONS
SWF-2801 : It is safer to always download the SHA1
SWF-2801 : ADT_DATA could not exist and thus pushed & co are failing
SWF-2801 : Download SHA1 only if SHA1 or target file aren’t existing
SWF-2801 : Deploy required add ons
SWF-2801 : Remove duplicated function
SWF-2801 : Download and install the add ons manager