Laravel 5.6 updates

Travis config update

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

vendor/barryvdh/laravel-debugbar/composer.json

@@ -10,10 +10,13 @@
         }
     ],
     "require": {
-        "php": ">=5.5.9",
-        "illuminate/support": "5.1.*|5.2.*|5.3.*|5.4.*|5.5.*",
-        "symfony/finder": "~2.7|~3.0",
-        "maximebf/debugbar": "~1.13.0"
+        "php": ">=7.0",
+        "maximebf/debugbar": "~1.15.0",
+        "illuminate/routing": "5.5.x|5.6.x",
+        "illuminate/session": "5.5.x|5.6.x",
+        "illuminate/support": "5.5.x|5.6.x",
+        "symfony/debug": "^3|^4",
+        "symfony/finder": "^3|^4"
     },
     "autoload": {
         "psr-4": {
@@ -22,5 +25,23 @@
         "files": [
             "src/helpers.php"
         ]
+    },
+    "minimum-stability": "dev",
+    "prefer-stable": true,
+    "extra": {
+        "branch-alias": {
+            "dev-master": "3.2-dev"
+        },
+        "laravel": {
+            "providers": [
+                "Barryvdh\\Debugbar\\ServiceProvider"
+            ],
+            "aliases": {
+                "Debugbar": "Barryvdh\\Debugbar\\Facade"
+            }
+        }
+    },
+    "require-dev": {
+        "illuminate/framework": "5.5.x"
     }
 }