`fast_knn` pass allowed parameters through to `kdtree.query and `KDTree`

[eltonlaw]

For KDTree currently using the default leafsize and for kdtree.query, the default eps, p and distance_upper_bound. Allow this to be modified.

fast_knn(data, k=3, eps=0, p=2, distance_upper_bound=np.inf, leafsize=10)