Fix double slashes with %~dp0 and use setlocal
Avoid using real symlinks/junctions in the bundle on windows.

They're only used in a couple of places:
- for the core node_modules, but NODE_PATH is set, so that isn't needed.
- for nested NPM package dependencies

For the package dependencies, use a simple text file instead of a
symlink
and do an explicit check and redirect in server.js if needed.
Add quotes for more portable bat file