v4.0.0: Release 4.0.0

• BREAKING CHANGE remove electron as direct dependency to allow using a self chosen version
• use binaries of meteor project version instead of meteor tool version
• update electron-packager
• kill hanging mongo process when closing in development mode on linux/osx
• add port config option / read PORT env in dev mode
• add config option to use external mongodb
• add support for electrify.local.json in development
• use mongo mmapv1 storage engine on windows only for mongo 3.2 (32 bit)