Merge pull request #35 from dekalee/feature/symfony3

Modify expression-language requirement to be compatible with sf3

composer.json

@@ -23,7 +23,7 @@
  "require": {
  "symfony/framework-bundle": ">=2.2",
  "symfony/security-bundle": ">=2.2",
- "symfony/expression-language": "~2.4",
+ "symfony/expression-language": ">=2.4",
  "doctrine/doctrine-bundle": "~1.2",
  "doctrine/common": "~2.2",
  "doctrine/dbal": "~2.2"