Generate module name seperated by '/' on Windows.

Summary: I think packager on different platform should generate same output if possible. So packager should replace '\\' in module name with '/' on Windows.

Closes facebook#2813

Reviewed By: @​svcscm

Differential Revision: D2458634

Pulled By: @martinbigio

packager/react-packager/src/DependencyResolver/Module.js

@@ -56,7 +56,7 @@ class Module {
               return this.path;
             }
 
-            return path.join(name, path.relative(p.root, this.path));
+            return path.join(name, path.relative(p.root, this.path)).replace(/\\/g, '/');
           });
       })
     );