broken unittest test_Stetson

[ryanjmccall]

FATS/test_library.py:286: a=a.calculateFeature(white_noise)

looks like the StetsonJ fit() function requires data[7] contain aligned error but the white_noise function doesn't generate it

[vBazilevich]

I came across the same issue. Based on AlignLC implementation which just selects measurements from both LCs which have the same MJD, aligned errors must be just a copies of the generated errors. Still, the test is failing.