OF-1093: Allow for empty/unknown user creation dates.

Some user providers might not be able to provide a creation date. There's no reason
that the admin page should fail over that.
Note that this commit completes commit 2746a7f4,
which had an correct but incomplete fix for the same problem.

src/plugins/search/src/web/advance-user-search.jsp

@@ -167,7 +167,7 @@
            <%= user.getName() %> &nbsp;
        </td>
        <td width="15%">
-           <%= JiveGlobals.formatDate(user.getCreationDate()) %> &nbsp;
+           <%= user.getCreationDate() != null ? JiveGlobals.formatDate(user.getCreationDate()) : "&nbsp;" %>
        </td>
         <td width="25%">
             <% long logoutTime = presenceManager.getLastActivity(user);

src/web/user-properties.jsp

@@ -270,7 +270,7 @@
             <fmt:message key="user.properties.registered" />:
         </td>
         <td>
-            <%= JiveGlobals.formatDate(user.getCreationDate()) %>
+            <%= user.getCreationDate() != null ? JiveGlobals.formatDate(user.getCreationDate()) : "&nbsp;" %>
         </td>
     </tr>
     <tr>