Remove useless dependencies & fragment Symfony dependencies

composer.json

@@ -6,17 +6,21 @@
     "homepage": "https://github.com/Orbitale/CmsBundle",
     "license": "MIT",
     "require": {
-        "php": ">=5.4.0",
-        "doctrine/orm": "^2.2.3",
+        "php": "^7.0",
         "behat/transliterator": "^1.0",
-        "doctrine/doctrine-bundle": "^1.2",
-        "sensio/framework-extra-bundle": "^2.3|^3.0",
-        "symfony/symfony": "^2.3|^3.0",
+        "doctrine/doctrine-bundle": "^1.5",
+        "doctrine/orm": "^2.4",
+        "symfony/asset": "^3.0",
+        "symfony/framework-bundle": "^3.0",
+        "symfony/templating": "^3.0",
+        "symfony/translation": "^3.0",
+        "symfony/twig-bundle": "^3.0",
+        "symfony/validator": "^3.0",
+        "symfony/yaml": "^3.0",
         "twig/twig": "^1.23|^2.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^4.8",
-        "symfony/swiftmailer-bundle": "^2.3|^3.0"
+        "phpunit/phpunit": "^6.0"
     },
     "suggest": {
         "javiereguiluz/easyadmin-bundle": "To manage your pages directly inside your CMS (view documentation)"