Update composer.json to enable symfony3

cause of request_stack usage instead of "isScopeActive" we need to enable symfony 2.7 as the latest lts version, 2.3 does not supprt the request_stack

Author: DZunke

composer.json

@@ -14,21 +14,21 @@
     "require": {
         "php": ">=5.3.2",
         "mjohnson/decoda": "6.*",
-        "symfony/twig-bundle": "~2.0",
-        "symfony/assetic-bundle": "~2.0",
-        "symfony/config": "~2.0",
-        "symfony/console": "~2.0",
-        "symfony/dependency-injection": "~2.0",
-        "symfony/framework-bundle": "~2.1",
-        "symfony/http-foundation": "~2.1",
-        "symfony/http-kernel": "~2.0",
-        "symfony/process": "~2.0",
-        "symfony/templating": "~2.0",
-        "symfony/yaml": "~2.0",
-        "sensio/distribution-bundle": ">=2.1"
+        "symfony/twig-bundle": "~2.7|~3.0",
+        "symfony/assetic-bundle": "~2.4",
+        "symfony/config": "~2.7|~3.0",
+        "symfony/console": "~2.7|~3.0",
+        "symfony/dependency-injection": "~2.7|~3.0",
+        "symfony/framework-bundle": "~2.7|~3.0",
+        "symfony/http-foundation": "~2.7|~3.0",
+        "symfony/http-kernel": "~2.7|~3.0",
+        "symfony/process": "~2.7|~3.0",
+        "symfony/templating": "~2.7|~3.0",
+        "symfony/yaml": "~2.7|~3.0",
+        "sensio/distribution-bundle": "~4.0|~5.0"
     },
     "require-dev": {
-        "symfony/symfony": "~2.1",
+        "symfony/symfony": "~2.7|~3.0",
         "satooshi/php-coveralls": "dev-master"
     },
     "autoload": {