Settings: More QuietHours improvements

Wasn't going to bother.  But might as well.
	Remove unnecessary imports.
	Fix low-dpi Dialog-text not centering.
	Use dip over sp for better layout.
	Add StateListDrawable for prettier
		dismiss clicking.

Change-Id: I0b863528b82ec7daa9048f1c71ff1c4da4c566bd