Libraries UI: remove underline on hover.

This changes the style of the inactive libraries/courses tab when hovering.

Only the active tab on the dashboard page gets the blue underline.
When hovering over an inactive tab, the color of the text changes,
but the underline does not appear.

cms/static/sass/views/_dashboard.scss

@@ -299,19 +299,21 @@
       line-height: $baseline*2;
       margin: 0 10px;
 
-      &.active, &:hover {
+      &.active {
         border-bottom: 4px solid $blue;
       }
 
+      &.active, &:hover {
+        a {
+          color: $gray-d2;
+        }
+      }
+
       a {
         color: $blue;
         cursor: pointer;
         display: inline-block;
       }
-
-      &.active a {
-        color: $gray-d2;
-      }
     }
   }