Allow each component to have its own colors and default to the global set

sass/form/tools.sass

@@ -3,6 +3,8 @@ $label-weight: $weight-bold !default
 
 $help-size: $size-small !default
 
+$label-colors: $form-colors !default
+
 .label
   color: $label-color
   display: block
@@ -22,7 +24,7 @@ $help-size: $size-small !default
   display: block
   font-size: $help-size
   margin-top: 0.25rem
-  @each $name, $pair in $colors
+  @each $name, $pair in $label-colors
     $color: nth($pair, 1)
     &.is-#{$name}
       color: $color