Fix cca-push ulimit command to work on both osx & linux
Fix cca-push ulimit command to work on both osx & linux

fixes MobileChromeApps/chrome-app-developer-tool#29

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