$.fn.decorateErrors can receive errors format from from provejs-express

[GreenRaccoon23]

Currently, $.fn.decorateErrors expects the errors object in the format {'': ''}, where the value for each key is a string. provejs-express sets the errors object in the format {'': [''...]}, where the value for each key is an array of strings.

This pull request allows the errors object to be in either format so that it can support provejs-express.

The commits from 2018-02-23 are already in the master branch of provejs-jquery, so you can ignore them. I'm not sure why git decided to include them in the pull request.