Create CONTRIBUTING.md
fix #60, use package.json to build the version string
Merge pull request #104 from yorkie/use-package

fix #60, use package.json to build the version string
modular: extract the 2 function `inetNtoa` and `inetAton` to utils
Merge pull request #105 from yorkie/simlify-code

modular: extract the 2 function `inetNtoa` and `inetAton` to utils
utils: should output the err.stack
Merge pull request #106 from yorkie/error-trace

utils: should output the err.stack
cake build