add symfony/expression-language dep

Author: ek9

composer.json

@@ -31,6 +31,7 @@
         "guzzle/http": "~3.0",
         "symfony/config": "~2.3||~3.0",
         "symfony/dependency-injection": "~2.2||~3.0",
+        "symfony/expression-language": "~2.2||~3.0",
         "symfony/http-kernel": "~2.3||~3.0",
         "symfony/http-foundation": "~2.3||~3.0"
     },