Reduce the minimum version required for symfony.

Author: curiosity26

composer.json

@@ -2,7 +2,7 @@
   "name": "curiosity26/angular-material-bundle",
   "description": "A bundle to integrate Angular Material to Symfony's Forms and Asset Management",
   "require": {
-    "symfony/symfony": "^3.1"
+    "symfony/symfony": "^2.4"
   },
   "require-dev": {
     "phpunit/phpunit": "^5.5"