By default, only staff members have to confirm their old email when
changing it. This commit adds a site setting that when enabled will
always ask the user to confirm old email.
It's very easy to forget to add `require 'rails_helper'` at the top of every core/plugin spec file, and omissions can cause some very confusing/sporadic errors.
By setting this flag in `.rspec`, we can remove the need for `require 'rails_helper'` entirely.