[mvp] authentication

[melvincarvalho]

There are 3 possible options for authentication:

1 WebID-TLS - not working in some browsers
2 Solid-OIDC - complex
3 SolidOS PKI - experimental

One of these is needed to get Solid-Lite to MVP

Or another strategy that is easy to implement

[melvincarvalho]

Another option is to use passportjs

If it returns a URI use that as a direct or indirect identifier

If it returns a literal preface it with urn:webid: to make it into a URI

[melvincarvalho]

(3) is selected for now, add some text about pluggable auth in the SLIPs and add SLIPs