Update lib/sugarcube/uiview.rb

added method rotation_to
Update spec/uiview_animation.rb

added test for rotate_to
Update README.md

updated with examples for rotate_to (animations)
Merge pull request #27 from mlohr/master

rotate_to updated with test and read-me
Merge pull request #26 from mlohr/patch-1

Merge mlohr's `rotate_to` method
some README changes.  thanks again, @mlohr!