Add Laravel 5.4 support

Author: ivanvermeyen

composer.json

@@ -21,13 +21,13 @@
     "require": {
         "php": ">=5.6.4",
         "guzzlehttp/guzzle": "^6.2",
-        "illuminate/notifications": "5.3.*",
-        "illuminate/support": "5.1.* || 5.2.* || 5.3.*"
+        "illuminate/notifications": "5.3.* || 5.4.*",
+        "illuminate/support": "5.1.* || 5.2.* || 5.3.* || 5.4.*"
     },
     "require-dev": {
         "mockery/mockery": "^0.9.5",
         "phpunit/phpunit": "5.*",
-        "orchestra/testbench": "3.3.x-dev"
+        "orchestra/testbench": "3.4.x-dev"
     },
     "autoload": {
         "psr-4": {