Speedup FastText tests (#1686)
Speedup FastText tests (#1686)

Current version of FastText is pure-python,
so CPU-bound processing with multiple workers in it is a bad idea.
Using workers=12 in a some tests increased execution time of tests.
gojomo/gensim,piskvorky/gensim,markroxor/gensim,RaRe-Technologies/gensim,piskvorky/gensim,RaRe-Technologies/gensim,markroxor/gensim,RaRe-Technologies/gensim,mattilyra/gensim,piskvorky/gensim,gojomo/gensim,mattilyra/gensim,gojomo/gensim,markroxor/gensim,gojomo/gensim,mattilyra/gensim,RaRe-Technologies/gensim