Shouldn't create / write to files under node_modules #68

Thanks for this project, it works great and is amazingly useful.

I noticed that type files are being generated for scss files loaded from libraries under node_modules, and being written to the library folder. This seems like a bad idea since these files aren't committed. In my case it meant that one of our commit checks passed on my machine but failed on the server, since the type files didn't exist there.

I think it would be best to avoid writing to node_modules by default.