Implement simple asset versioning task

A task to allow one to define zero or more JSON files and keys to create or update with the current timestamp.

By default, the boilerplate will maintain a './assets.json' file which should be imported by the Web framework and applied to compiled assets.

loconfig.json

@@ -62,6 +62,11 @@
                 "./www/**/*.html",
                 "./assets/scripts/**/*"
             ]
-        }
+        },
+        "versions": [
+            {
+                "outfile": "./assets.json"
+            }
+        ]
     }
 }