- Add hover style

- Add default theme reference
- Revert react-grid-layout to 1.3.4

Signed-off-by: Dave Richer <dave@imexsystems.ca>

client/src/App/App.styles.scss

@@ -1,9 +1,14 @@
 //Global Styles.
 @import "react-big-calendar/lib/sass/styles";
+
 .ant-menu-item-divider {
   border-bottom: 1px solid #74695c !important;
 }
 
+.ant-menu-dark .ant-menu-item:hover {
+  background-color: #1890ff !important;
+}
+
 .imex-table-header {
   display: flex;
   flex-wrap: wrap;