docker-stats: container realtime performance

![screen shot 2014-11-02 at 1 00 54 pm](https://cloud.githubusercontent.com/assets/9376831/4877006/e9fc32e2-62d9-11e4-897e-a538c046e495.png)


docker-stats brings native performance metrics to Docker. 3 primary goals:
1) Command Line Docker Metrics
![screen shot 2014-11-02 at 2 35 15 pm](https://cloud.githubusercontent.com/assets/9376831/4877197/96b49f50-62e0-11e4-818d-e13b5df07744.png)


2) REST API
- Ease of streaming performance metrics directly via Docker API
- Leverage time series best practices to reduce overhead

Example:
![screen shot 2014-11-02 at 5 17 29 pm](https://cloud.githubusercontent.com/assets/9376831/4877799/43edb6f0-62f7-11e4-8a30-5807add9c576.png)


3) Ease of integration
Enable the community to add metrics via go interface
Easy to move data via serializable JSON