Implemented the HttpHeaderAntiForgeryAttribute

1.- HttpHeaderAntiForgeryTokenAttribute
2.- Substituted the SimplePostVariableParameterBindingAttribute
Merge remote-tracking branch 'upstream/master'

Conflicts:
	MVC4/PersonaMVC4Example/Controllers/PersonaController.cs
	MVC4/PersonaMVC4Example/Views/Account/Login.cshtml
Synchronizing with remote...

eliminating SimplePostParameterBinding
Trying again
Merge branch 'master' of https://github.com/shanselman/AspNetPersonaId

Conflicts:
	MVC4/PersonaMVC4Example/Controllers/PersonaController.cs
Added EnsureSuccessStatusCode.
Merge pull request #2 from rmbrunet/master

HttpHeaderAntiForgeryTokenAttribute