Feature Request: Change UIDs with node-client

When answering to #1143 I thought this should be possible to be done with the node-client itself.
I'm thinking of an interface like:

```
$ keybase uid list
(1) keybase.io/username
(2) Name (private)
(3) Name (business)

$ keybase uid delete
Which UID do you want to delete?
(1) keybase.io/username
(2) Name (private)
(3) Name (business)
[1...3]:

$ keybase uid delete name@provider.com
Name (private)
Is this the UID you wnat to remove? [y/N]

$ keybase uid add
Provide some details:
Name:
Email:
Comment:
Is this correct? [y/N]
```

Start by reviewing the node-client entry points for UID management and the related issue #1143. Confirm how existing UIDs are listed, added, and deleted, then define the command behavior shown in this issue; done means the list, delete, and add flows work with confirmation and input handling.

Written by the indexing model from the issue text.