Fixes bug 923049 - Removed risk of sensitive data exposure.

@peterbe r?

This bug was a bit hard to find: the cause is that ``ALL_POSSIBLE_FIELDS`` was not a constant, and I would simply extend it with restricted fields whenever a user would log in. As that is a module variable, it is not reloaded at every page call. So, if a user logs in, the list gets updated with the restricted fields for every single visitor. That led to people being able to see emails and urls without being logged in. 

SuperSearch is currently disabled, we will turn it back on when this is merged / released.