Remove unnecessary h2 element on create account

We added these headings during the last account creation and login form
redesign but on recollection I'm not sure they're needed.

The messages are pretty much redundant with the h1 heading,
and now h2 elements have a margin-top of 1em it adds too much whitespace.

Change-Id: Ice5e8bf23cc00bf00835e7dc26acc33182654ec5