Add "verify your authenticator now" form to configuration view

This patch adds "verify your authenticator" form to configuration view.
If user regenerates Authenticator configuration but does not use
Authenticator after that, there's small "actions required" label on the
top bar.

There was no obvious way to validate the configuration, and signing in
with Authenticator was additional, unnecessary step.

Resolves #31
Merge branch 'master' of github.com:ojarva/sso-frontend