Time only? (and a few notes about readme)

[martinsiden]

Hi!

Thanks for this awesome picker! Great job. I would like to request a new feature that would only let user select the time without any date.

Also, I noticed that the readme wants you to override CSS using this selector:

#my-div .datetime-picker { background-color: blue; }

But the rendered class is actually called "ng2-datetime-picker". And in the example for overriding date format the import statement is stated twice.