Composer fix

Author: michalsanger

composer.json

@@ -1,18 +1,19 @@
 {
     "name": "michalsanger/quadtree",
-    "description": "An easy-to-modify quadtree.",
+    "description": "An easy-to-modify Quadtree with standard 2D implementation.",
     "keywords": ["quadtree", "collision detection"],
-    "license": ["MIT"],
+    "license": "MIT",
     "authors": [
         {
             "name": "Michal Sänger",
             "email": "michal.sanger@gmail.com"
         }
     ],
     "autoload": {
-        "psr-4": {
-            "Quadtree\\": "Quadtree"
-        }
+       "classmap": ["Quadtree/"]
+    },
+    "require": {
+        "php": ">=5.3.0"
     },
     "require-dev": {
         "nette/tester": "v1.2.0"