[MRG] Locality Sensitive Hashing for approximate nearest neighbor search(GSoC)

OK, I had missed the fact that LSHForest was a replacement for these, and not for the *Neighbors objects.

Beautiful design choice, I really like it.

So my remark doesn't apply (neither does the one about the missing predict method).

However, I would then like to see the LSHForest object be added to the various neighboors objects, in parallel to the KDTree and BallTree. That's the way to give value to users.