[HttpFoundation] Basic auth in url is broken when using PHP CGI/FPM

Request#getUser() and Request#getPassword() introduced in
aecfd0a8917370edd237120352749141ffa85362 do not handle the lack of
PHP_AUTH_USER and PHP_AUTH_PW in $this->server when using PHP-FPM. Use
$this->headers instead.
Furthermore, the test of empty password now expects an empty string
instead of NULL according to a450d002f253e32e77d5c2bd3e490435c68a8c09.

Author: Kdecherf

Request.php

@@ -949,7 +949,7 @@ public function getPort()
      */
     public function getUser()
     {
-        return $this->server->get('PHP_AUTH_USER');
+        return $this->headers->get('PHP_AUTH_USER');
     }
 
     /**
@@ -959,7 +959,7 @@ public function getUser()
      */
     public function getPassword()
     {
-        return $this->server->get('PHP_AUTH_PW');
+        return $this->headers->get('PHP_AUTH_PW');
     }
 
     /**

Tests/RequestTest.php

@@ -209,7 +209,7 @@ public function testCreate()
         $this->assertEquals(80, $request->getPort());
         $this->assertEquals('test.com', $request->getHttpHost());
         $this->assertEquals('testnopass', $request->getUser());
-        $this->assertNull($request->getPassword());
+        $this->assertSame('',$request->getPassword());
         $this->assertFalse($request->isSecure());
 
         $request = Request::create('http://test.com/?foo');