Authentication

@aslawter , @mikeymurph77 
How about putting the errors inline, and setting `flash[:error]` to `"Could not sign you up. Check the form below for errors"`?

Like this:

```erb
<%= form.label :password %>
<%= form.password_field :password %>
<%= form.object.errors.full_messages_for(:password) %>
```

etc., for all form fields. Then the flash is simple and you can show errors next to the failing fields.