implement KSVD with sklearn interface style

[tksmd]

Implement KSVD with sklearn interface. You can implement fit method and reuse some other method provided by SparceCodingMixin like the following class.

• https://github.com/scikit-learn/scikit-learn/blob/master/sklearn/decomposition/dict_learning.py#L941-L1109

We should follow same package structure of sklearn like spmimage.decomposition.ksvd.py. Also implement test code to run KSVD.

[sutkss]

ksvdを計算する関数内でOMPの計算をscikit learnのsparce_codingで行っている.
sparse_encodeはjoblibで並列化できるが, 引数をうまく渡せてない.