More reliable "login into auth"
More reliable "login into auth"

fixes #184 again

Purpose of the change:

`TeleportProcess.loginIntoAuthService()` did not _properly_ login into
the auth service before (it just validated an identity). Turns out, to
actually "log in" one has to call at least one Auth API method
successfully.

I've added a call to API.GetLocalDomain() and count a successful login
only if that function succeeds.

aashley/teleport,ajvb/teleport,yacloud-io/teleport,bshelton229/teleport,ajvb/teleport,suedadam/teleport,yacloud-io/teleport,tidalf/teleport,tidalf/teleport,aashley/teleport,suedadam/teleport,gravitational/teleport,bshelton229/teleport,tidalf/teleport,ajvb/teleport,bshelton229/teleport,aashley/teleport,tidalf/teleport,gravitational/teleport,yacloud-io/teleport,aashley/teleport,sokoow/teleport,gravitational/teleport,yacloud-io/teleport,sokoow/teleport,sokoow/teleport,gravitational/teleport,suedadam/teleport,gravitational/teleport,yacloud-io/teleport,ajvb/teleport,gravitational/teleport,yacloud-io/teleport,sokoow/teleport,yacloud-io/teleport,aashley/teleport,sokoow/teleport,bshelton229/teleport,tidalf/teleport,suedadam/teleport,ajvb/teleport,bshelton229/teleport,sokoow/teleport,suedadam/teleport