Add UI_DISABLE_DATASETS and UI_DISABLE_RESERVATIONS to defs file.
These variables allow for a finer grain control over how these newer
experimental features are presented to users.  possible values for
these variables:

        0: [the default]  include these features in the UI for all
        1: only show these features to admins in "red dot" mode
        2: never show these features in the UI (even for admins)

sites that can't or aren't using these features can use this to
remove them from the UI to help prevent their users from becoming
confused.