[scikit-learn] Call for reviewers for 0.18 release

[Andreas Mueller]

Hey folks.

We are preparing to release 0.18 and we're a bit short on reviewers (I'm 
semi-online myself).
If any of you want to pitch in, please have a look at the PRs with the 
0.18 milestone:

https://github.com/scikit-learn/scikit-learn/pulls?q=is%3Aopen+milestone%3A0.18+is%3Apr

Thanks,
Andy