Optimized login form - delegated CSRF token creation to thymeleaf

Also added additional test to verify behaviour.

Fixes gh-1039
Fix issues with DeviceDelegatingViewResolverAutoConfiguration

- Log to the correct class
- Set Auto-configure after Thymeleaf hint on main class instead of
  internal static class
- Use 'thymeleafViewResolver' bean name instead of class for
  conditional bean checks
- Fix class name in properties documentation

Fixes gh-1052
Make properties to sanitize configurable in EnvironmentEndpoint.

Add "key" to default keys that will be sanitized. fixes #1027