add app hold state

resolves #684
Does this ever get called? The case seems to be
1. app configs has not been viewed OR there is no current user, and
2. the current user is not an admin
i.e., the current user is not an admin and app configs have not been viewed.

However, this flash seems to get overwritten by the ```app_setup_check``` flash from line 40. I'm fine leaving this in as a failsafe, but I haven't been able to trigger this flash notice.