Separate data-source and processing logic

- Add more examples to config.json.example
- Move build-status to bamboo-build-status
- Move processing logic out of bamboo-rest data-source and into bamboo-build-status
- Remove caching (too complicated for now)
- Move data-source logic into separate mixin
- Make bamboo-rest use new data-source mixin
- Add andThrow() to logger.error() calls