Added a implementation and updated deps versions

Author: Nyholm

composer.json

@@ -15,17 +15,18 @@
     "prefer-stable": true,
     "require": {
         "php": ">=5.4",
-        "php-http/discovery": "^0.2.0",
+        "php-http/discovery": "^0.4",
         "php-http/client-implementation": "^1.0",
-        "php-http/message-factory": "^0.2.0",
+        "php-http/message-factory": "^1.0",
         "php-http/plugins": "dev-master",
         "symfony/framework-bundle": "^2.7|^3.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^4.4",
+        "php-http/guzzle5-adapter": "dev-master",
         "symfony/symfony": "^2.7|^3.0",
         "polishsymfonycommunity/symfony-mocker-container": "~1.0",
-        "matthiasnoback/symfony-dependency-injection-test": "0.*"
+        "matthiasnoback/symfony-dependency-injection-test": "^0.7"
     },
     "autoload": {
         "psr-4": {