AppBadges: buggy custom label behaviour

[sohkai]

At least in Permissions, but I suspect elsewhere as well, editing the custom label of an AppBadge does not automatically edit the other badges rendered on the page.

The popover also should not show "custom label" if no custom label has been applied yet.

In general, the AppBadge implementation in the client (from https://github.com/aragon/aragon/pull/983/files) should be re-done completely.

[sohkai]

This may be because App.js's label handlers do not emit events on the identityEvents$ observable used elsewhere (e.g. useIdentitiesActions.js).

Related to #660, we most likely want to redo how these events are wired throughout the client.