made fill position adhere to self.bounds for scaling purposes

[davidtperk]

1. Fill layer should be calculated on the view's bounds, not its frame. Transformations aren't applied to the frame property when the view is scaled, so the fill level isn't properly adjusted. From Apple:

Views have both a frame (coordinates in superview's coordinate system) and bounds (coordinates in own coordinate system) property, but if you transform a view, you should not use or rely on the frame property anymore. If you are using transformations, work with the bounds property only, not the frame property, as transformations are applied to the bounds, but aren't necessarily reflected accurately in frame.

2. Added kCAMediaTimingFunctionEaseInEaseOut timing function to fillTo()'s CAKeyframeAnimation for a nice, cold, smooth pour.

[antiguab]

@dtp5 - dude, solid catch!! No clue how I missed this PR. Do you mind updating the branch (doubt there will be conflicts) and I can merge it? Thanks again!

[dimasno1]

will someone merge this branch into master?)