Combined a presenting animation with `setTintAdjustmentMode` & `overlayview`.

The background overlay and button dimming animation was animated after presenting or dismissing animtation.
Fixed two step animations to just one step.
fixed a bug #89: `presentPopoverAsDialogAnimated:` does not show any popover.
Merge pull request #100 from ksjun/fix-dialog

fixed a bug #89: `presentPopoverAsDialogAnimated:` does not show any popover.
Merge pull request #98 from ksjun/fix-animation

Combined a presenting animation with `setTintAdjustmentMode` & `overlayview`
Merge branch 'upstream/master'

Conflicts:
	WYPopoverController/WYPopoverController.m