bug#23744: guix: npm don't run

["Jovany Leandro G.C" <bit4bit@riseup.net>]

HI,
this distro it's amazing i very happy using it.

i install **guix package -i npm** version *6.0.0* node 
and when try **npm** this throws:

~~~
Error: Cannot find module '../lib/npm.js'
    at Function.Module._resolveFilename (module.js:438:15)
    at Function.Module._load (module.js:386:25)
    at Module.require (module.js:466:17)
    at require (internal/module.js:20:19)
    at /gnu/store/y98akn298a47sn3f7c19pzw98jw9a14b-node-6.0.0/bin/npm:26:13
    at Object.<anonymous>
(/gnu/store/y98akn298a47sn3f7c19pzw98jw9a14b-node-6.0.0/bin/npm:76:3)
at Module._compile (module.js:541:32) at Object.Module._extensions..js
(module.js:550:10) at Module.load (module.js:456:32)
    at tryModuleLoad (module.js:415:12)
~~~

i fix for working:

create a file $HOME/bin/npm
~~~
#!/bin/sh
node $HOME/.guix-profile/lib/node_modules/npm/bin/npm-cli.js $@
~~~

append to $HOME/.bashrc

~~~
export PATH=$HOME/bin:$PATH
~~~

and that's it, now npm works only for local install

for my case i run **npm install ionic@beta** and run **node
~/node_modules/ionic/bin/ionic**
and works :)

I hope to be helpful
thanks,