Enable VCS Root with SSH Key Authentication

[raelyard]

Issue details

I want to use FluentTC to create VCS Roots with uploaded SSH Key

Relates to issue

close #110

Checklist

• [ ] All unit tests passed on build server
• [ ] Acceptance test(s) covers new/modified functionality
• [ ] Code coverage is at least the same or higher
• [ ] Breaking change in public API

Example of using new/modified functionality

var vcsRoot = connectedTc.CreateVcsRoot(__ => __
                .AgentCleanFilePolicy(AgentCleanFilePolicy.AllIgnoredUntrackedFiles)
                .AgentCleanPolicy(AgentCleanPolicy.Always)
                .AuthMethod(AuthMethod.TeamcitySshKey)
                .Branch("refs/head/develop")
                .BranchSpec("+:refs/head/feature/*")
                .Id("VcsRootId")
                .IgnoreKnownHosts()
                .Name("VcsRootName")
                .ProjectId("ProjectId")
                .CheckoutSubModule()
                .UploadedKey("keyName")
                .Url(new Uri("http://www.gooogle.com"))
                .UseAlternates()
                .UserNameStyle(UserNameStyle.AuthorName));

[raelyard]

Apologies for the delay. Accepted all your feedback except for renaming the method. Gave my comment there in that the name matches what is in the TeamCity UI and I expect that is probably preferable.