Fixed the required version of Markdom Handler Interface dependency.

Author: Martin Brecht-Precht

composer.json

@@ -23,6 +23,6 @@
   },
   "require": {
     "php": ">=5.3",
-    "markdom/handler-interface": "~1.0"
+    "markdom/handler-interface": "^1.0.2"
   }
 }