Support for "ComparisonChain"

Hi, great job, sir! :)
I often include Guava in my projects, but I always end up using like 1% of it (mostly collections and predicates). The problem on Android is it's huge methods footprint, which I guess your lib is trying to solve.

I have only one request. Could you add class [ComparisonChain](https://github.com/google/guava/blob/master/guava/src/com/google/common/collect/ComparisonChain.java)? It has almost none dependencies, shouldn't be a problem :)