Add name and scope to init config

When running `npm init` it's not currently possible to set the package name via config.  An `--init-name` flag seems like it should exist.


Additionally, having a scope configured for `init` to use when it auto defines the name based on the directory seems like a good idea.


```sh
$ mkdir foo
$ cd foo
$ npm init --init-scope=@gar -y
```

... should make a package name `@gar/foo`