Optimize autoload prefix in composer.json

By having more specific autoload prefixes it is possible to reduce the number of stat calls made. Also it prevents possible collisions.

composer.json

@@ -7,6 +7,6 @@
         "php": ">=5.3.0"
     },
     "autoload": {
-        "psr-0": { "org\\bovigo\\vfs": "src/main/php" }
+        "psr-0": { "org\\bovigo\\vfs\\": "src/main/php" }
     }
 }