Set default protocol to HTTPS for loading Google Chart API
Set default protocol to HTTPS for loading Google Chart API

That allow the library to be loaded from PhoneGap that is loaded from the file:// protocol.

Fix #23

nbering/angular-google-chart,areverberi/angular-google-chart,angular-google-chart/angular-google-chart,angular-google-chart/angular-google-chart,nbering/angular-google-chart,areverberi/angular-google-chart