Add npm flag to deps command

[garritfra]

We are currently able to install clio dependencies via clio deps add greeter. We should also be able to install npm dependencies this way. One way to do this is to add a flag to the command like so: clio deps add --npm express
If you come up with alternative ideas, please comment them on this issue.

[mindrones]

Related:

• https://github.com/npm/npm-registry-fetch
• #109