public_field: make sub-field visible

[Stefan Klein]

Hi couch users,

i got some application specific data in my user documents and have to make
one of the fields visible to other users.
public_field works fine, for top level fields. I try to make a sub field
visible.

{
"_id": "org.couchdb.user:someuser",
"_rev": "somerev",
"appData" : {
    "field" : "should be visible",
    "secretfield" : "should not be visible"
}