Laravel 5.6 updates

Travis config update

Removed HHVM script as Laravel no longer support HHVM after releasing 5.3

vendor/symfony/http-kernel/Tests/Exception/MethodNotAllowedHttpExceptionTest.php

@@ -12,6 +12,19 @@ class MethodNotAllowedHttpExceptionTest extends HttpExceptionTest
         $this->assertSame(array('Allow' => 'GET, PUT'), $exception->getHeaders());
     }
 
+    public function testWithHeaderConstruct()
+    {
+        $headers = array(
+            'Cache-Control' => 'public, s-maxage=1200',
+        );
+
+        $exception = new MethodNotAllowedHttpException(array('get'), null, null, null, $headers);
+
+        $headers['Allow'] = 'GET';
+
+        $this->assertSame($headers, $exception->getHeaders());
+    }
+
     /**
      * @dataProvider headerDataProvider
      */