Hide "Activity Item" menu tab for non-logged in/non-admin users

[PatriciaMoller]

There is no reason for ordinary users to be able to access the individual Activity Items. Having such a similarly named tab is confusing and there is chance of players entering and seeing the answers before playing the game.

[pjotrsavitski]

Only menu item got hidden, the access to listing and single activity item page still remains. There are links to those from within the Full View of Activity. Unless there is a way to show all the necessary information without leaving the page, this will not change.