If untagged traffic hits zerodot, send it to http://.

* Furthremore, only autoredirect zerodot to mdot if actually enabled
* Currently, sometimes users land on https:// and it's not yet zero-rated. So let's send them to http:// where odds will be better.
* Currently, sometimes users land on zerodot when mdot is in the profile and they get autoredirected to mdot anyway, but the operator config isn't actually enabled. So let's provide the user a confirmation screen in this case to make sure it's what the user wanted, instead of autoredirecting.
* Yurik: Reworked to use bit flags instead of 3 bools

Change-Id: I7b423334d158a7739a36d8608030de337c34b39a