Fix array equality matcher

Hi,

I think the given test cases are pretty self-descriptive. :relaxed:

If you agree with this change I'll submit a PR to update the documentation, this part specifically:

> Note: the beEqualTo matcher is using the regular == Scala equality. However in the case of Arrays, Scala == is just using reference equality, eq, for Arrays. So the beEqualTo matcher has been adapted to transform Arrays to Seqs before checking for equality, so that Array(1, 2, 3) === Array(1, 2, 3) (despite the fact that Array(1, 2, 3) != Array(1, 2, 3)).

Cheers!