StyleCopCmdLine is a wrapper project to make it possible to easily call StyleCop from a command line or a PowerShell script. It is (since 22.214.171.124) build against the version of StyleCop on GitHub as opposed to the older version on Codeplex.
For more details on the usage see the this repo's Wiki.
For a discussion of its usage within a TFS 2015 vNext build see this blog post.
A true TFS vNext build task using this wrapper assembly can be found in this repo.