Conditionally define signing tool.
Conditionally define signing tool.

This allow creating of packages for testing without signature
(to avoid confusion).

jahanzaibbahadur/rubyinstaller,vemmaverve/rubyinstaller,shirosaki/rubyinstaller,modulexcite/rubyinstaller,dreamauya/rubyinstaller,dreamauya/rubyinstaller,auyaauya/rubyinstaller,suvarnaraju/rubyinstaller,haonaturel/rubyinstaller,jaym/rubyinstaller,zorosteven/rubyinstaller,Rugbyman21/rubyinstaller,zorosteven/rubyinstaller,auyaauya/rubyinstaller,zorosteven/rubyinstaller,leonhooijer/rubyinstaller,dreamauya/rubyinstaller,oneclick/rubyinstaller,oneclick/rubyinstaller,Rugbyman21/rubyinstaller,vemmaverve/rubyinstaller,haonaturel/rubyinstaller,haonaturel/rubyinstaller,vemmaverve/rubyinstaller,leonhooijer/rubyinstaller,leonhooijer/rubyinstaller,shirosaki/rubyinstaller,jahanzaibbahadur/rubyinstaller,Rugbyman21/rubyinstaller,auyaauya/rubyinstaller,suvarnaraju/rubyinstaller,modulexcite/rubyinstaller,jahanzaibbahadur/rubyinstaller,shirosaki/rubyinstaller,oneclick/rubyinstaller,jaym/rubyinstaller,jaym/rubyinstaller,suvarnaraju/rubyinstaller,modulexcite/rubyinstaller