suggestion: detect location of node_modules

[ycmjason]

Sometimes I use concat to build my javascript project. And sometimes my projects use some modules from NPM. So I think it would be a good idea to detect the location from node_modules using require.resolve().

So instead of
concat ./node_modules/.../...js ./index.js
we could do
concat npm_module_name ./index.js

What do you think?

[ycmjason]

after some thought i think this wouldn't be useful.