Make name on user optional

[rasmusebbesen]

Or remove it completely. The bare minimum of information needed on the user should be email and password.

[steffendsommer]

We need to look at how JWTKeychain handles profile information and auth credentials. We talked about different approaches and decided not to include this for the first major release. Some ideas to consider when picking this up again:

• Having profile information separate from auth credentials. Adds a lot of flexibility and might open up for dealing with other types of authentication (e.g. by LinkedIn token etc)
• Subclassing a user model
• Using protocols to be able to customize the user model

Feel free to add if I missed anything @rasmusebbesen @BrettRToomey @siemensikkema