Issue 3413 b2g tos pp

@jedp - can you review this PR? This builds on #3408, so we should get that out of the way first.

 TOS/PP updates for B2G/Firefox OS Marketplace

* On mobile devices, show the RP TOS/PP below the Persona TOS/PP on the authentication page.
* On mobile devices, show the RP TOS/PP below the email list on the email picker page to users who have not previously visited the site.
* When signing into Marketplace (as indicated by experimental_forceIssuer) on a mobile device, hide the RP info at the top of the screen.

The ephemeral instance with this PR combined with #3408 is tos-pp.personatest.org

fixes #3413