Limit persona reviewers permissions compared to addon reviewers (bug 1076278)

Fixes [bug 1076278](https://bugzilla.mozilla.org/show_bug.cgi?id=1076278)
I would split that one in two distinct decorators `addons_reviewer_required` and `personas_reviewer_required`. Benefits: no more `only` logic and ability to combine/chain both to make an equivalent of `any_reviewer_required` only in use for the `home` view.