Remove `req.resume` from `app.enableAuth` (1.x, 2.x)

Remove `req.pause` and `req.resume` from `app.enableAuth`
 - they are no longer needed, the request starts paused and there is
   no other middleware that would resume it before us.
 - when we resume the request after authentication, we force all
   other async operations (like sharedCtor) to call pause & resume too,
   otherwise data are lost

Close https://github.com/strongloop/strong-remoting/issues/84

/to @raymondfeng @ritch please review
/cc @fabien