Add support for serialization / deserialization.
Add AssemblyInformationalVersion attribute
Remove unused references
Add support for building v2.0, v3.5, v4.0, v4.5, v4.5.1

You can build new releases by using .\semver.ps1 -packageVersion 1.1.2
and final nuget package is available in bin\semver\1.1.2\AnyCPU\Release
Make serialization constructor private.
Merge branch 'peters-master'