implement BatchBALD and LAL-RL strategy

[JlsBssmnn]

I wrote my bachelor thesis about Active Learning Query Strategies. As a part of the thesis I implemented the two strategies BatchBALD and LAL-RL for ALiPy. To verify the correctness of the implementations, I tested the strategies on some datasets that were mentioned in the papers, and compared my results to the results in the papers. I found out, that my results were very close the the results in the paper.

[tangypnuaa]

Hi, thanks for your great work and sorry for the late reply. I have just finished an urgent task which took me more than a month. Now I have time to improve ALiPy, and your PR will be soon viewed and discussed.