Added an MSI test run task and descriptions for MSI tasks
Added an MSI test run task and descriptions for MSI tasks

	rake msi:install    # install the product
	rake msi:test_run   # run the installer without installing the product
	rake msi:uninstall  # uninstall the product

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