fix iOS7 crash attempt to fix #46 and #39
fix iOS7 crash
attempt to fix #46 and #39

bastian-meier/cordova-plugin-background-geolocation,bastian-meier/cordova-plugin-background-geolocation,mauron85/cordova-plugin-background-geolocation,redskyit/cordova-plugin-background-geolocation,GeoTob/cordova-plugin-background-geolocation,redskyit/cordova-plugin-background-geolocation,gkachru/cordova-plugin-background-geolocation,GeoTob/cordova-plugin-background-geolocation,gkachru/cordova-plugin-background-geolocation,mauron85/cordova-plugin-background-geolocation,mauron85/cordova-plugin-background-geolocation