Auto-install platforms if none installed, was recently broken, fixed
Auto-install platforms if none installed, was recently broken, fixed

If a project has no platforms installed, cca automatically installs platforms.
This was done by auto-upgarde.js and was accidentally removed in recent
refactoring in 97ab08ee9679e22f5de293bff356a00a873ff9d7
Reverting to this behaviour

Related to issue #272

liqingzhu/mobile-chrome-apps,xiaoyanit/mobile-chrome-apps,chirilo/mobile-chrome-apps,guozanhua/mobile-chrome-apps,MobileChromeApps/mobile-chrome-apps,liqingzhu/mobile-chrome-apps,wudkj/mobile-chrome-apps,MobileChromeApps/mobile-chrome-apps,chirilo/mobile-chrome-apps,hgl888/mobile-chrome-apps,hgl888/mobile-chrome-apps,liqingzhu/mobile-chrome-apps,chirilo/mobile-chrome-apps,hgl888/mobile-chrome-apps,wudkj/mobile-chrome-apps,hgl888/mobile-chrome-apps,chirilo/mobile-chrome-apps,guozanhua/mobile-chrome-apps,xiaoyanit/mobile-chrome-apps,wudkj/mobile-chrome-apps,xiaoyanit/mobile-chrome-apps,hgl888/mobile-chrome-apps,xiaoyanit/mobile-chrome-apps,MobileChromeApps/mobile-chrome-apps,MobileChromeApps/mobile-chrome-apps,wudkj/mobile-chrome-apps,guozanhua/mobile-chrome-apps,guozanhua/mobile-chrome-apps,liqingzhu/mobile-chrome-apps,hgl888/mobile-chrome-apps,hgl888/mobile-chrome-apps