Add a formula for moco

Moco is an easy setup stub framework.
More information can found in [https://github.com/dreamhead/moco](https://github.com/dreamhead/moco).

Integration, especially based on HTTP protocol, e.g. web service, REST etc, is wildly used in most of our development.
Moco can do it by provider a quick and fake server to help development.
e.g. look at `cmake.rb` for a formula with a good test.