Extended in several ways

Hi,

i added some features, maybe you want to merge them:
- [x] join String for nested option is a setting
- [x] hostname is now the config hostname and not os.hostname() by default
- [x] switched unit testing to mocha (+ sinon and sandboxed-module)
- [x] added many tests
- [x] internal used functions are no longer in the prototype of the instance