SemVer 2.0 support for the CHANGELOG

[cdwillie76]

I created a pull request to update the SEMVER regex pattern to support SerVer 2.0. This is my first attempt with code changes to a node app and open to learning how to improve it. I split out the parse functions since I was getting a webpack error when I exported the other functions to support the unit tests. Thanks!

#318

[xeronimus]

thanks for the contribution. PR merged, see #321