Merge pull request #18 from tsantos84/master

Added symfony Yaml 4 to project dependencies

Author: nilportugues

composer.json

@@ -25,7 +25,7 @@
     ],
     "require": {
         "php": ">=5.6.0",
-        "symfony/yaml": "2.*|3.*"
+        "symfony/yaml": "2.*|3.*|4.*"
     },
     "require-dev": {
         "phpunit/phpunit": "5.*",