FIX : fix kfold balance due to int rounding
FIX : test due to KFold change
FIX : better fix of KFold balance
fix doctest
Removed an unnecessary if statement in KFold __iter__ method.
Improved the test that checks the balance of sizes of folds returned by KFold.
DOC Corrected the docstring of KFold about the sizes of the folds.
TST : improve test_kfold_balance test
update what's new
TST : improve again  test_kfold_balance test
Merge pull request #1726 from agramfort/round_kfold

MRG : fix kfold balance due to int rounding