Add required constraint to required fields

This ensures the aria-required attr will be set correctly.
Merge remote-tracking branch 'origin/nb-identity-reset-password' into nb-identity-reset-password
Merge remote-tracking branch 'origin/nb-identity-reset-password' into nb-identity-reset-password

Conflicts:
	identity/app/controllers/SigninController.scala
Use abstracted form els for ResetController fields
Remove server-side email population from reset

This can be passed in the hash as progressive enhancement. This means
caching isn't broken for the page and we don't need to sanitise the
logs. It also improves the URL structure.