Bug in cache key caused the /users view to display a bunch of duplicates

[TheNotary]

I hit the bug when I manually generating a bunch of example db entries and didn't realize it would effect you guys, but now that I think about it, every week, the bug would manifest itself due to the new non db backed Fab records.

The code version of the story is that the cache key needed to address the user of the fab in some way, as it stood, it didn't and only respected update_at which clearly isn't enough to cut it.

# notice that this key will be the same for every FAB created at the same moment in time
# regardless if it's for two different users, thus at the beginning of the week, you'll
# see a lot of the same user profile
cache([@fab.updated_at, @fab_editable, adminy?])

The attached PR fixes the bug and re-enables caching to improve app response time tremendously for /users. Let me know if there was another bug you observed preventing use of caching.

caching == cake