Better configurability for UI

[MrJoy]

I'm using SideKiq-Cron, which behaves very badly when the DB gets flushed (it no longer sees any cron configuration until the server is restarted), so I'd prefer to disable this feature globally and leave flushing the DB to a more organized ops runbook.

Similarly, I'd like to be able to disable the CLI as well.

Really, all of this would be fairly easily achievable for my needs if I had a way of telling redmon to load an extra stylesheet that I could use to hide the relevant DOM elements. I'm not concerned from a security perspective -- just a fat-fingers/uninformed-users perspective.