ResetPasswordController now uses ID's SafeLogger

Log messages are now being sanitised. Also improves the logging for
the controller.
House style
Merge remote-tracking branch 'origin/master' into reset-password-controller-with-safelogging

Conflicts:
	identity/app/controllers/SigninController.scala
Merge pull request #1565 from guardian/reset-password-controller-with-safelogging

ResetPasswordController now uses ID's SafeLogger