Allow Symfony 4.

Author: derrabus

.travis.yml

@@ -14,6 +14,7 @@ matrix:
         - php: 5.5
         - php: 5.6
         - php: 7.0
+        - php: 7.1
           env: DEPENDENCIES=dev
         - php: hhvm
 

composer.json

@@ -12,12 +12,12 @@
     ],
     "require": {
         "php": ">=5.3.3",
-        "symfony/yaml": "~2.3|~3.0"
+        "symfony/yaml": "^2.3 || ^3.0 || ^4.0"
     },
     "require-dev": {
-        "composer/composer": "1.0.*@dev",
+        "composer/composer": "^1.0",
         "phpspec/prophecy-phpunit": "~1.0",
-        "symfony/filesystem": "~2.2"
+        "symfony/filesystem": "^2.2 || ^3.0 || ^4.0"
     },
     "autoload": {
         "psr-4": { "Incenteev\\ParameterHandler\\": "" }