Allow setting for minutes to hour roll over feature.

[wholladay]

Feature Request:

Provide a method to turn off incrementing/decrementing the hours field when the minutes field wraps around. For example, if the user enters 9 in the hours field and then click on the down spinner for the minutes field (so it goes to 45 for example), do not decrement the hours field to 8. The most common use case for us is that the user works from left to right, so the user enters the hour and then the minutes, and is not expecting the minutes field to change the hours field. Therefore we would very much like to have the option of turning this behavior off.

[bastienmoulia]

Not sure how to do that because the changes method are inside the NgbTime class.