Bug 1023663 - [User story] Calendar day view should start at 8 AM r=millermedeiros

Currently, the patch is for ui review. It is not ready for code review.
when I said to override the `this.changeDate()`  it was to avoid the duplication of `this._getScrollToHour()`... (every time you change the date on the DayView it should scroll to hour, unless we pass the `onlyToday: true`...)

ideally the call is just:  `this.changeDate(date)` or `this.changeDate(date, { onlyToday: true })`