Add initial support for adding settings.

Adds "Add Setting" button to table, and shows a popup with form
elements for adding a new setting. Does not yet add setting to the db.

webui/source/templates/admin/add-setting.tpl

@@ -0,0 +1,21 @@
+<table>
+    <thead>
+        <th>Name</th>
+        <th>Type</th>
+    </thead>
+    <tbody>
+        <tr>
+            <td>
+                <input type="text" id="settings_add_name" value="" />
+            </td>
+            <td>
+                <select id="settings_add_tpe">
+                    <option value="int">Integer</option>
+                    <option value="bool">Boolean</option>
+                    <option value="string">String</option>
+                    <option value="string_list">String List</option>
+                </select>
+            </td>
+        </tr>
+    </tbody>
+</table>

webui/source/templates/admin/settings.tpl

@@ -22,6 +22,7 @@
         <tr>
             <td colspan="2">
                 <input type="button" id="settings_save" name="save" value="Save" />
+                <input type="button" id="settings_add" name="add" value="Add Setting" />
             </td>
         </tr>
     </tfoot>