Feature/822 addr verif credentials

I have created a new Address Verification Settings custom setting with Protected visibility. Before it had Public visibility, and it's not possible to change it. I deleted the old one. I hope this does not cause any issues, @jlantz.

Also, I have changed the Address Verification Settings page to stop displaying the Auth ID and Token, both as the user enters them, and in view mode.

I have not found any place where the settings are made available to the rest of the system through a global method (this was the third point for this item in the security review). @davidhabib or @kbromer, do you know of any?
@ceiroa All of these messages to the end user need to use custom labels so they can be translated.  I'm oking with this code going in, as long as you have a seperate scrumDo User Story to do the translation work.