Fix Windows bug.

Author: Joel Denning

lib/node-loader-core.js

@@ -1,10 +1,13 @@
 import path from "path";
+import url from "url";
 
 let configPromise;
 
-const configPath = path.join(
-  process.cwd(),
-  process.env.NODE_LOADER_CONFIG || "node-loader.config.js"
+const configPath = url.pathToFileURL(
+  path.join(
+    process.cwd(),
+    process.env.NODE_LOADER_CONFIG || "node-loader.config.js"
+  )
 );
 
 let loadingConfig = false;