Added event firing for remote-to-local syncing.
Added event firing for remote-to-local syncing.

This is not yet done automatically; remote-to-local syncing must be prompted via the `getDriveChanges` function.

Also added Drive id caching for created directories (currently only used for the app directory).
Also added a semi-related TODO.
Also corrected a typo.
xiaoyanit/mobile-chrome-apps,wudkj/mobile-chrome-apps,hgl888/mobile-chrome-apps,chirilo/mobile-chrome-apps,guozanhua/mobile-chrome-apps,chirilo/mobile-chrome-apps,liqingzhu/mobile-chrome-apps,MobileChromeApps/mobile-chrome-apps,hgl888/mobile-chrome-apps,hgl888/mobile-chrome-apps,wudkj/mobile-chrome-apps,chirilo/mobile-chrome-apps,xiaoyanit/mobile-chrome-apps,guozanhua/mobile-chrome-apps,xiaoyanit/mobile-chrome-apps,liqingzhu/mobile-chrome-apps,liqingzhu/mobile-chrome-apps,MobileChromeApps/mobile-chrome-apps,guozanhua/mobile-chrome-apps,xiaoyanit/mobile-chrome-apps,MobileChromeApps/mobile-chrome-apps,wudkj/mobile-chrome-apps,guozanhua/mobile-chrome-apps,hgl888/mobile-chrome-apps,MobileChromeApps/mobile-chrome-apps,hgl888/mobile-chrome-apps,liqingzhu/mobile-chrome-apps,chirilo/mobile-chrome-apps,hgl888/mobile-chrome-apps,hgl888/mobile-chrome-apps,wudkj/mobile-chrome-apps