Ensure that prerelease comparison matches spec

[thisandagain]

From #14

[nrbrook]

Will this ever be fixed?

[thisandagain]

Hi @nrbrook. I haven't been focused on maintaining this module given most of my development is now in Swift these days. That said, I realize I am very behind in reviewing pull requests on this repo. I will try to triage these PRs as soon as possible.

[nrbrook]

This pull request #30 contains a fix (from #14 which was closed) and other project updates