composer: change package type and use stable version

Author: xalopp

composer.json

@@ -1,21 +1,7 @@
 {
-    "repositories": [
-        {
-            "type": "package",
-            "package": {
-                "name": "squizlabs/php_codesniffer",
-                "version": "master",
-                "source": {
-                    "url": "https://github.com/squizlabs/PHP_CodeSniffer.git",
-                    "type": "git",
-                    "reference": "master"
-                }
-            }
-        }
-    ],
     "name": "mayflower/mo4-coding-standard",
     "description": "PHP CodeSniffer ruleset implementing the MO4 coding standards extending the Symfony coding standards.",
-    "type": "library",
+    "type": "phpcodesniffer-standard",
     "keywords": [
         "phpcs",
         "Symfony",
@@ -36,11 +22,12 @@
         "source": "https://github.com/mayflower/mo4-coding-standard"
     },
     "require-dev": {
-        "squizlabs/php_codesniffer": "3.x-dev",
         "phpunit/phpunit": "^4.0 || ^5.0 || ^6.0"
     },
     "require": {
+        "squizlabs/php_codesniffer": "^3.0",
+        "escapestudios/symfony2-coding-standard": "^3.0",
+        "dealerdirect/phpcodesniffer-composer-installer": "^0.4.3",
         "php": ">=5.4.0"
-    },
-    "minimum-stability": "dev"
+    }
 }