Add Symfony's dependency injection manager as a dependency.

composer.json

@@ -45,7 +45,8 @@
         "symfony/routing": "^3.4",
         "symfony/http-foundation": "^3.4",
         "symfony/config": "^3.4",
-        "symfony/http-kernel": "^3.4"
+        "symfony/http-kernel": "^3.4",
+        "symfony/dependency-injection": "^3.4"
     },
     "require-dev": {
         "phpunit/phpunit": "~4.8",

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "14aaf0dd50482ab820337a0691231b3d",
+    "content-hash": "ca77036cf8ae88d3f3679effc3fea17c",
     "packages": [
         {
             "name": "gettext/gettext",
@@ -218,6 +218,55 @@
             ],
             "time": "2018-07-02T15:55:56+00:00"
         },
+        {
+            "name": "psr/container",
+            "version": "1.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/php-fig/container.git",
+                "reference": "b7ce3b176482dbbc1245ebf52b181af44c2cf55f"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/php-fig/container/zipball/b7ce3b176482dbbc1245ebf52b181af44c2cf55f",
+                "reference": "b7ce3b176482dbbc1245ebf52b181af44c2cf55f",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Psr\\Container\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "PHP-FIG",
+                    "homepage": "http://www.php-fig.org/"
+                }
+            ],
+            "description": "Common Container Interface (PHP FIG PSR-11)",
+            "homepage": "https://github.com/php-fig/container",
+            "keywords": [
+                "PSR-11",
+                "container",
+                "container-interface",
+                "container-interop",
+                "psr"
+            ],
+            "time": "2017-02-14T16:28:37+00:00"
+        },
         {
             "name": "psr/log",
             "version": "1.0.2",
@@ -480,6 +529,77 @@
             "homepage": "https://symfony.com",
             "time": "2018-10-02T16:33:53+00:00"
         },
+        {
+            "name": "symfony/dependency-injection",
+            "version": "v3.4.17",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/dependency-injection.git",
+                "reference": "aea20fef4e92396928b5db175788b90234c0270d"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/dependency-injection/zipball/aea20fef4e92396928b5db175788b90234c0270d",
+                "reference": "aea20fef4e92396928b5db175788b90234c0270d",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.5.9|>=7.0.8",
+                "psr/container": "^1.0"
+            },
+            "conflict": {
+                "symfony/config": "<3.3.7",
+                "symfony/finder": "<3.3",
+                "symfony/proxy-manager-bridge": "<3.4",
+                "symfony/yaml": "<3.4"
+            },
+            "provide": {
+                "psr/container-implementation": "1.0"
+            },
+            "require-dev": {
+                "symfony/config": "~3.3|~4.0",
+                "symfony/expression-language": "~2.8|~3.0|~4.0",
+                "symfony/yaml": "~3.4|~4.0"
+            },
+            "suggest": {
+                "symfony/config": "",
+                "symfony/expression-language": "For using expressions in service container configuration",
+                "symfony/finder": "For using double-star glob patterns or when GLOB_BRACE portability is required",
+                "symfony/proxy-manager-bridge": "Generate service proxies to lazy load them",
+                "symfony/yaml": ""
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.4-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Component\\DependencyInjection\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony DependencyInjection Component",
+            "homepage": "https://symfony.com",
+            "time": "2018-10-02T12:28:39+00:00"
+        },
         {
             "name": "symfony/event-dispatcher",
             "version": "v3.4.17",