Switch to stable version constraints where possible

framework/core/composer.json

@@ -13,10 +13,10 @@
         "tobscure/json-api": "dev-master",
         "tobscure/permissible": "dev-master",
         "misd/linkify": "1.1.*",
-        "oyejorge/less.php": "dev-master",
-        "intervention/image": "dev-master",
-        "ezyang/htmlpurifier": "dev-master",
-        "psr/http-message": "^1.0@dev",
+        "oyejorge/less.php": "~1.5",
+        "intervention/image": "^2.3.0",
+        "ezyang/htmlpurifier": "^4.6.0",
+        "psr/http-message": "^1.0",
         "zendframework/zend-diactoros": "^1.1",
         "nikic/fast-route": "^0.6",
         "dflydev/fig-cookies": "^1.0"
@@ -33,5 +33,5 @@
             "Flarum\\": "src/"
         }
     },
-    "minimum-stability": "dev"
+    "minimum-stability": "stable"
 }