sandstone: color in panel-footer, fixes #411

sandstone/_bootswatch.scss

@@ -175,12 +175,15 @@ input,
   @include box-shadow(none);
 
   .panel-heading,
-  .panel-title,
-  .panel-footer {
+  .panel-title {
     @extend .sandstone;
     color: #fff;
   }
 
+  .panel-footer {
+    @extend .sandstone;
+  }
+
   &-default {
     .panel-heading,
     .panel-title,

sandstone/bootstrap.css

@@ -6695,14 +6695,19 @@ input:focus,
   box-shadow: none;
 }
 .panel .panel-heading,
-.panel .panel-title,
-.panel .panel-footer {
+.panel .panel-title {
   font-size: 11px;
   line-height: 22px;
   font-weight: 500;
   text-transform: uppercase;
   color: #fff;
 }
+.panel .panel-footer {
+  font-size: 11px;
+  line-height: 22px;
+  font-weight: 500;
+  text-transform: uppercase;
+}
 .panel-default .panel-heading,
 .panel-default .panel-title,
 .panel-default .panel-footer {

sandstone/bootswatch.less

@@ -175,12 +175,15 @@ input,
   .box-shadow(none);
 
   .panel-heading,
-  .panel-title,
-  .panel-footer {
+  .panel-title {
     .sandstone;
     color: #fff;
   }
 
+  .panel-footer {
+    .sandstone;
+  }
+
   &-default {
     .panel-heading,
     .panel-title,