Use ES6 spread operator instead of .concat for nav items

ui/src/side_nav/containers/SideNav.js

@@ -34,28 +34,21 @@ const SideNav = React.createClass({
   },
 
   renderUserMenuBlockWithCustomLinks(customLinks, logoutLink) {
-    return [<NavHeader key={0} title="User" />].concat(
+    return [
-      customLinks
+      <NavHeader key={0} title="User" />,
-        .map(({name, url}, i) =>
+      ...customLinks.map(({name, url}, i) =>
-          <NavListItem
+        <NavListItem key={i + 1} useAnchor={true} isExternal={true} link={url}>
-            key={i + 1}
+          {name}
-            useAnchor={true}
+        </NavListItem>
-            isExternal={true}
+      ),
-            link={url}
+      <NavListItem
-          >
+        key={customLinks.length + 1}
-            {name}
+        useAnchor={true}
-          </NavListItem>
+        link={logoutLink}
-        )
+      >
-        .concat(
+        Logout
-          <NavListItem
+      </NavListItem>,
-            key={customLinks.length + 1}
+    ]
-            useAnchor={true}
-            link={logoutLink}
-          >
-            Logout
-          </NavListItem>
-        )
-    )
   },
 
   render() {