Github extended symver tag strings being stripped

[jspaleta]

tag strings of the form "1.2.3-rc.1+build.1" and "1.2.3+build.1" should be legal symver but Bonsai is unable to process github tags with prerelease (-) and/or metadata (+) suffixes.

As per discussion, it appears that Bonsai is stripping information past the patch level

I'll setup a repository with non functional example tags with prerelease and metadata sections for testing and add them in as an additional comment.

[pzupan]

Pull Request #139