I have an application that uses the email migration API, and it authenticates via ClientLogin, as I believe is the only support way of doing it. Am I wrong about that? The reason I ask is that ClientLogin is now "depreciated" and supposedly will go away April 20, 2015. Will the email migration API support OAuth 2.0? If so, how exactly is the ability to perform a migration on behalf of a user done (without knowing the user password)?