As this package got messed up after the Unity's 4.6 update , I've updated it to be better and please give it a one more try also it's free (for now :) )-
A simple day and night cycle system that has a lot of small details, while it also looks good!
Features :-
Moving Clouds : Moving clouds are added just to give it a bit
more dynamic feel.
Stars : Stars have a twinkle effects you can have multiple layers of stars same goes for clouds and yeah they also move
Cloud Shadows : these are little expensive on the machine there are two prefabs one without this effect.
Comments : All the scripts are well commented so it should be
easy to understand.
Web Demo
Enjoy The Asset