Laravel 5.6 updates

Travis config update

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

vendor/maximebf/debugbar/src/DebugBar/RequestIdGenerator.php

@@ -11,15 +11,33 @@
 namespace DebugBar;
 
 /**
- * Request id generator based on the $_SERVER array
+ * Basic request ID generator
  */
 class RequestIdGenerator implements RequestIdGeneratorInterface
 {
+    protected $index = 0;
+
     /**
      * @return string
      */
     public function generate()
     {
-        return md5(serialize($_SERVER) . microtime());
+        if (function_exists('random_bytes')) {
+            // PHP 7 only
+            return 'X' . bin2hex(random_bytes(16));
+        } else if (function_exists('openssl_random_pseudo_bytes')) {
+            // PHP >= 5.3.0, but OpenSSL may not always be available
+            return 'X' . bin2hex(openssl_random_pseudo_bytes(16));
+        } else {
+            // Fall back to a rudimentary ID generator:
+            //  * $_SERVER array will make the ID unique to this request.
+            //  * spl_object_hash($this) will make the ID unique to this object instance.
+            //    (note that object hashes can be reused, but the other data here should prevent issues here).
+            //  * uniqid('', true) will use the current microtime(), plus additional random data.
+            //  * $this->index guarantees the uniqueness of IDs from the current object.
+            $this->index++;
+            $entropy = serialize($_SERVER) . uniqid('', true) . spl_object_hash($this) . $this->index;
+            return 'X' . md5($entropy);
+        }
     }
 }