Guest control: Cleaned methods involved in fetching/handling

- Moves guest user caching from User class to app container for
  simplicity.
- Updates test to use simpler $this->users->guest() method for
  consistency.
- Streamlined helpers to avoid function overlap for simplicity.
- Extracted user profile dropdown while doing changes.

app/Http/Middleware/ApiAuthenticate.php

@@ -31,7 +31,7 @@ class ApiAuthenticate
     {
         // Return if the user is already found to be signed in via session-based auth.
         // This is to make it easy to browser the API via browser after just logging into the system.
-        if (signedInUser() || session()->isStarted()) {
+        if (!user()->isGuest() || session()->isStarted()) {
             if (!$this->sessionUserHasApiAccess()) {
                 throw new ApiAuthException(trans('errors.api_user_no_api_permission'), 403);
             }
@@ -53,6 +53,6 @@ class ApiAuthenticate
     {
         $hasApiPermission = user()->can('access-api');
 
-        return $hasApiPermission && hasAppAccess();
+        return $hasApiPermission && user()->hasAppAccess();
     }
 }

app/Http/Middleware/Authenticate.php

@@ -12,7 +12,7 @@ class Authenticate
      */
     public function handle(Request $request, Closure $next)
     {
-        if (!hasAppAccess()) {
+        if (!user()->hasAppAccess()) {
             if ($request->ajax()) {
                 return response('Unauthorized.', 401);
             }

app/Http/Middleware/PreventAuthenticatedResponseCaching.php

@@ -20,7 +20,7 @@ class PreventAuthenticatedResponseCaching
         /** @var Response $response */
         $response = $next($request);
 
-        if (signedInUser()) {
+        if (!user()->isGuest()) {
             $response->headers->set('Cache-Control', 'max-age=0, no-store, private');
             $response->headers->set('Pragma', 'no-cache');
             $response->headers->set('Expires', 'Sun, 12 Jul 2015 19:01:00 GMT');