Add skinny-logback module for colorful logging

Just forked spring-boot's implementation and extracted minimum modules. 

https://github.com/spring-projects/spring-boot/tree/1.1.x/spring-boot/src/main/java/org/springframework/boot/logging/logback

![screen shot 2014-10-17 at 12 49 08 am](https://cloud.githubusercontent.com/assets/19658/4665576/2697bc6c-554c-11e4-844e-d680a3bb0f17.png)