Merge pull request #7 from ihor-sviziev/patch-1

Add json php extension to dependencies list

Author: balbuf

composer.json

@@ -9,6 +9,7 @@
   }],
   "license": "MIT",
   "require": {
-    "php": ">=5.4"
+    "php": ">=5.4",
+    "ext-json": "*"
   }
 }