Added feature to fix #1523
ENH decision_function now returns #votes and scaled scores.
TST Added test to assertain correlation of decision function and prediction
FIX Implemented _check_is_fitted for OvO similar to the one for OvR
FIX Correct and separate the scaling logic for scores
TST Add decision_function tests to check for votes/scores

ovo_ties test will use decision function to calculate votes and score.
COSMIT Undo aggressive pep8
ENH use the decision_function to compute the prediction