Merge branch 'date-picker-hover' into 'master'

Fixed hover of date picker calendar

## What does this MR do?

Fixes the hover styling of days on the datepicker dropdown in the issuable sidebar.

## Screenshots (if relevant)

![hover](/uploads/2514dc772187da33c54f8b6324202189/hover.gif)

See merge request !4786

app/assets/stylesheets/framework/dropdowns.scss

@@ -461,10 +461,12 @@
       }
     }
-    .ui-state-active,
-    .ui-state-hover {
-      color: $md-link-color;
-      background-color: $calendar-hover-bg;
+    .ui-datepicker-calendar {
+      .ui-state-hover,
+      .ui-state-active {
+        color: #fff;
+        border: 0;
+      }
     }
     .ui-datepicker-prev,