add composer autoload

Author: Alexey Gavrilov

composer.json

@@ -14,5 +14,7 @@
   "require": {
     "php": ">=5.3.0"
   },
-  "autoload": {}
+  "autoload": {
+    "psr-4": {"DnodeSyncClient\\": "src/"}
+  }
 }