added more tests for BayesianModel.predict
added more tests for BayesianModel.predict

ankurankan/pgmpy,jhonatanoliveira/pgmpy,sandeepkrjha/pgmpy,pgmpy/pgmpy,jhonatanoliveira/pgmpy,khalibartan/pgmpy,khalibartan/pgmpy,sandeepkrjha/pgmpy,ankurankan/pgmpy,pgmpy/pgmpy