Form Validation `.valid-feedback` and `.valid-tooltip` are unstyled

Created by: pat270

This adds styles for .valid-feedback and .valid-tooltip. If those items aren't supposed to have styles:

 @mixin form-validation-state($state, $color) {
  ...
       ~ .#{$state}-feedback,
       ~ .#{$state}-tooltip {
         display: block;
       }
  ...
}

needs to be changed.