Issue 2669 tos pp above button

This is a two part TOS/PP update.

First, the Persona TOS/PP text is *only* supposed to be shown to unauthenticated users before they enter their email address. Because it is never shown anywhere else, I removed all other Persona TOS/PP references.

Second, the request in #2669 is to place the Persona TOS/PP text above the submit button. This is done in both the dialog and the main site /signin page.