Support GitVersion

[savornicesei]

Hi,
CC.NET cannot succesfully build a project using git as source control and GitVersion for versioning.
GitVersion fails with the error

GitTools.WarningException: It looks like the branch being examined is a detached Head pointing to commit '3bd952f'. Without a proper branch name GitVersion cannot determine the build version.
at GitVersion.GitVersionFinder.EnsureHeadIsNotDetached(GitVersionContext context)
at GitVersion.GitVersionFinder.FindVersion(GitVersionContext context)
at GitVersion.ExecuteCore.<>c__DisplayClass6_0.b__0(IRepository repo)
at GitVersion.GitPreparer.WithRepository[TResult](Func`2 action)
at GitVersion.ExecuteCore.ExecuteGitVersion(String targetUrl, String dynamicRepositoryLocation, Authentication authentication, String targetBranch, Boolean noFetch, String workingDirectory, String commitId, Config overrideConfig, Boolean noCache)
at GitVersion.SpecifiedArgumentRunner.Run(Arguments arguments, IFileSystem fileSystem)
at GitVersion.Program.VerifyArgumentsAndRun()

This is caused by using git checkout -q -f origin\branch_name instead of git checkout -q -f ref\heads\branch_name or git checkout -b origin\branch_name (according to official documentation and this answer on StackOverflow).