switch to transcoder 2.0, fix symfony dependency version

Author: Stephan Wentz

composer.json

@@ -20,13 +20,13 @@
     ],
     "require": {
         "php": ">=5.5.0",
-        "brainbits/transcoder": "~1.0"
+        "brainbits/transcoder": "~2.0"
     },
     "require-dev": {
         "phpunit/phpunit": "~4.5",
-        "symfony/config": "~2.3.0",
-        "symfony/dependency-injection": "~2.3.0",
-        "symfony/http-kernel": "~2.3.0",
+        "symfony/config": "^2.3",
+        "symfony/dependency-injection": "^2.3",
+        "symfony/http-kernel": "^2.3",
         "matthiasnoback/symfony-config-test": "^1.4",
         "matthiasnoback/symfony-dependency-injection-test": "^0.7.6"
     },