add new schema for item rating output (also modifies current behaviour)
add schema for current stdlib/items output
fix users/list schema for several users
change users/list schema

Make user name the element content. Rename the root element from
'user-list' to 'users'. Add 'unique' constraints for user id and
name.
add schema for stdlib/releases/list

Does not reflect current output, but the output as it should and will be.
add a schema for candidates/list as well (does not reflect for current output)