Fix confusmat error described in issue #35

[asbisen]

This fix changes the interface to confusmat from

confusmat(k::Integer, gts::IntegerVector, preds::IntegerVector)

to

function confusmat(gts::IntegerVector, preds::IntegerVector)

here k is calculated automatically.

[BMasinde]

It would be nice if this pull request was merged with master.

[Mrinalini97]

i somehow still get the same issue even now,somehow