Updates

Changelog

- Factored out statistic related code into [libstats](https://github.com/japaric/stats.rs)
- Sampling is done with a different number of iterations each time (following an arithmetic progression)
- Perform linear regression as part of the analysis phase
- Preserve sampling order in some plots
- Flatten directory hierarchy of the generated files/plots
- Bring up to date with rust nigthly
- Automatic documentation generation and upload via travis