v0.1

v0.1:

• Finish GPU and GPU SCAN with CUDA. And the the top K is selected by _bucket algorithm_. Details can be found in https://github.com/imwithye/CUDA-K-Nearest-Neighbors. Bucket selection algorithm is published on http://www.math.grinnell.edu/~blanchaj/Research/Research.html#ggkspaper and implemented by Yiwei, imwithye@gmail.com
• Finish CPU SCAN algorithm