Description

Currently, score() method returns the mean accuracy
https://github.com/scikit-learn/scikit-learn/blob/14031f6/sklearn/base.py#L324

which is different from the scoring function supplied by user in constructor:
https://github.com/scikit-learn/scikit-learn/blob/14031f6/sklearn/linear_model/logistic.py#L1500

This is confusing, because as a user I would expect score() to use the same scoring function specified.

Steps/Code to Reproduce

Versions

In [3]: scipy.__version__
Out[3]: '0.17.1'

In [4]: numpy.__version__
Out[4]: '1.11.1'

In [7]: sklearn.__version__
Out[7]: '0.18.1'