Support for CsvHelper 3.0

[daheOnGitHub]

Hey, first, thank you very much for your project!
Any suggestions for the pre-released CsvHelper Version 3.0?
Is this CsvHelper.Excel Version still valid for the new release?

[christophano]

There have been quite a few changes to the api in version 3, and I've spoken to Josh (briefly) about them (see JoshClose/CsvHelper#596).
I do hope to be able to update to support version 3 though.