add link_rel_parser to autoload since it is not a class-based file. (from http://stackoverflow.com/questions/16273746/composer-packages-autoloading-non-class-based-files)

Author: aaronpk

composer.json

@@ -17,5 +17,10 @@
   ],
   "require": {
       "php": ">=5.3.0"
+  },
+  "autoload": {
+    "files": [
+      "src/IndieWeb/link_rel_parser.php"
+    ]    
   }
 }