Display name null because user has no name

[ionwyn]

When the user logs in, Toolbar takes a user's name for display. The API returns null for the user name's key. This can happen because:

• Upon signing up with Spotify, the user did not specify a name.
• The user did not sign up using Spotify.

I'm not sure which one it is, there may be other ways that the API returns null for a user's name.'

An idea is, when user's name is null, we simply display userID