Update jQuery to v1.12.4 (#4551)

Fix #4384

public/vendor/VERSIONS

@@ -6,7 +6,7 @@ File(s): /vendor/plugins/jquery.areyousure/jquery.are-you-sure.js
 Version: 1.9.0
 
 File(s): /vendor/plugins/jquery/jquery.min.js
-Version: 1.11.3
+Version: 1.12.4
 
 File(s): /vendor/plugins/semantic/semantic.min.js
 Version: 2.3.1

public/vendor/librejs.html

@@ -18,7 +18,7 @@
         <tr>
           <td><a href="./plugins/jquery/jquery.min.js">jquery.min.js</a></td>
           <td><a href="http://www.freebsd.org/copyright/freebsd-license.html">Expat</a></td>
-          <td><a href="https://code.jquery.com/jquery-1.11.3.min.js">jquery-1.11.3.min.js</a></td>
+          <td><a href="https://code.jquery.com/jquery-1.12.4.min.js">jquery-1.12.4.min.js</a></td>
         </tr>
         <tr>
           <td><a href="./plugins/semantic/semantic.min.js">semantic.min.js</a></td>