update badges to use the theme colors sass map

scss/_badge.scss

@@ -27,16 +27,6 @@
   top: -1px;
 }
 
-// scss-lint:disable QualifyingElement
-// Add hover effects, but only for links
-a.badge {
-  @include hover-focus {
-    color: $badge-link-hover-color;
-    text-decoration: none;
-  }
-}
-// scss-lint:enable QualifyingElement
-
 // Pill badges
 //
 // Make them extra rounded with a modifier to replace v3's badges.
@@ -51,26 +41,8 @@ a.badge {
 //
 // Contextual variations (linked badges get darker on :hover).
 
-.badge-default {
-  @include badge-variant($badge-default-bg);
-}
-
-.badge-primary {
-  @include badge-variant($badge-primary-bg);
-}
-
-.badge-success {
-  @include badge-variant($badge-success-bg);
-}
-
-.badge-info {
-  @include badge-variant($badge-info-bg);
-}
-
-.badge-warning {
-  @include badge-variant($badge-warning-bg);
-}
-
-.badge-danger {
-  @include badge-variant($badge-danger-bg);
+@each $color, $value in $theme-colors {
+  .badge-#{$color} {
+    @include badge-variant($value);
+  }
 }

scss/mixins/_badge.scss

@@ -1,11 +1,12 @@
-// Badges
-
-@mixin badge-variant($color) {
-  background-color: $color;
+@mixin badge-variant($bg) {
+  @include color-yiq($bg);
+  background-color: $bg;
 
   &[href] {
     @include hover-focus {
-      background-color: darken($color, 10%);
+      @include color-yiq($bg);
+      text-decoration: none;
+      background-color: darken($bg, 10%);
     }
   }
 }