Laravel 5.4 compatibility (#22)

* Update composer to work with Laravel 5.4
* work with new 5.4 interfaces
* add flush state
* modernize factory in line with 5 + 5.4 changes
* add the file engine
- Updated by SuperSeb92

Author: SuperSeb92

composer.json

@@ -11,7 +11,7 @@
     ],
     "require": {
         "php": ">=5.6.4",
-	"laravel/framework": "5.3.*"
+	"laravel/framework": "5.4.*"
     },
     "autoload": {
         "psr-4": {