Not compatible with Angular 1.8

[oliversalzburg]

Could also affect 1.7. I assume it's due to reliance on prebinding. All passed arguments are not merged into params, because this.options is undefined:

https://github.com/beenote/angular-material-datetimepicker/blob/gh-pages/js/angular-material-datetimepicker.js#L376