Fix intrinsicContentSize dependence on custom images.

[DanSkeel]

Before the fix custom images were scaled to match fixed 44 point height. Now intrinsicContentSize depends on size of custom image to prevent image scaling.

Hi. I hope I don't miss anything, but it works for me.

[DanSkeel]

Probably it's a bad idea, because a tappable area may become less than 44 points. So there should be other solution for custom sized "stars"

[DanSkeel]

1. Images less than 44 pt won't scale
2. height of ratingView will match the size of custom images but it won't be less than 44 pts.

[hsousa]

Oh, forgot to mention in the review but: Thanks for this! 😄