User manager: support for disabling an account

[ahenket]

The user manager underlying code seems properly prepared for dealing with rendering and updating the disabling/enabling of a user account. The UI however does not render Disabled and hence does not let you set/unset that

We manage this feature through our own user manager, but it makes sense to update the default user manager for it, especially since the server and client code are already equipped for handling it.

I tried creating a PR for this, but I don't understand how the bower setup works: it ignores any page change I make.

[duncdrum]

@ahenket that seems like a very welcome feature addition.

are you actually building the usermanager existdb/usermanager or the dashboard?