Fix regression: options page doesn't load common.js

As the options.html page referenced the common.js file with a relative
path, but it was moved, that reference broke. This change fixes this.

Change-Id: Ia47ddff4f214e9d0ca61c2c00a635e024509d9ba
diff --git a/src/options/options.html b/src/options/options.html
index dec47e2..6edd040 100644
--- a/src/options/options.html
+++ b/src/options/options.html
@@ -39,7 +39,7 @@
       <div class="actions"><button id="save" data-i18n="save"></button></div>
     </form>
     <div id="save-indicator"></div>
-    <script src="common/common.js"></script>
+    <script src="../common/common.js"></script>
     <script src="options.js"></script>
   </body>
 </html>