Sanitization

[cjslep]

#63 begins the process of sanitizing fields that are to be displayed in an application. It doesn't cover them all, additional things like preferredUsername and name and others will also need sanitization.

This feature needs to be flexible/extendable, so that it is applied recursively to nested structures, and so different applications can whitelist the differing fields in vocabularies that need sanitization treatment.

This'll be an intersting problem to solve...