[BugFix] test_coverage and MKLThreads miniconda supported

[YLTsai0609]

Hi @titoeb

Thanks for your great repo so that I can study RecWalk(2019) in Python.

Currently I found out there is only one python-based RecWalk implementation on github.

It's your repo! I'm glad that I have a chance to contribute.

I fix 1 bug and add miniconda support of MKLThreads.

1. test_coverage bug:

utils.py line 7

item_counts = np.zeros(Train.shape[0], dtype=np.int32) should be Train.shape[1]

Train.shape : (users, items).

I validate it by example.ipynb. The RecModel.NaiveBaseline should give us coverage = 1.0 (which makes sense).

2. MKLThreads miniconda supported.

I don't have libmkl_rt.so for ctypes.CDLL function in base_model.py line 191 and 193.

After checked this

It turned out I installed miniconda instead of anaconda. miniconda use libmkl_rt.dylib which is slower.

But we can prevent miniconda user from the error.