Add Laravel 5.6 Support

Author: irazasyed

composer.json

@@ -14,8 +14,8 @@
     "require": {
         "php": ">=5.6.4",
         "guzzlehttp/guzzle": "^6.2",
-        "illuminate/notifications": "5.3.* || 5.4.* || 5.5.*",
-        "illuminate/support": "5.1.* || 5.2.* || 5.3.* || 5.4.* || 5.5.*"
+        "illuminate/notifications": "5.3.* || 5.4.* || 5.5.* || 5.6.*",
+        "illuminate/support": "5.1.* || 5.2.* || 5.3.* || 5.4.* || 5.5.* || 5.6.*"
     },
     "require-dev": {
         "mockery/mockery": "^0.9.5",