Take the user to the main menu if they've already authenticated

[iambmelt]

If the user has already authenticated, we shouldn't prompt them for credentials or consent again.

[iambmelt]

Tagging as a bug because this is a known issue

[iambmelt]

From SignInActivity

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_signin);
    if (User.isOrg()) {
        mAuthenticationManager.connect(this);
    } else if (User.isMsa() && mLiveAuthClient.loginSilent(this)) {
        // mLiveAuthClient.loginSilent returns false if the app is closed or restarts
        start();
    }
    ButterKnife.inject(this);
}

[iambmelt]

Confirming this issue - doesn't look like this'll be ready for MVP.