Revert "Disambiguating permissions on index page"

This was the commit which broke [#49520767] and [#49523761]. Deploying this should fix those stories.

This reverts commit 0d8f559fd9a3dbb53c82b4d1bd680183f25d9b48.

https://www.pivotaltracker.com/story/show/49523761
https://www.pivotaltracker.com/story/show/49520767
Straightening out ownership of copied activities

[#49085561] The issue seems to be with the edit immediately after the copy. If the user saves the activity off that edit, it gets re-saved without an owner…?
Hidden field in the form was screwing up ownership

We probably don't need that code.
LightweightActivity : add is_official checkbox available to admins.

https://www.pivotaltracker.com/story/show/49219767
[#49219767]
activities/index is decided into official, and user generated activities

[#49219831]
https://www.pivotaltracker.com/story/show/49219831