#2003 - Add admin/movies screen.

Added admin/movies screen analogous to the admin/graphics screen so the user can:
- see how FFmpeg is configured (path and version, similar to toolkits in admin/graphics)
- get some instructions on how to install FFmpeg if not found
- change the movie_allow_uploads setting
- ask Gallery to rebuild their movie thumbs
Specifics:
- admin_movies, admin_movies.html (new) - new Movies admin screen
- ffmpeg.png (new) - logo for admin screen
- movie::get_ffmpeg_version (new) - return version number and date of FFmpeg
- form_uploadify.html - change admin message if movie uploads are disabled
- gallery_event::admin_menu - added Movies link to Settings
- xss_data.txt - updated golden file for unit tests

modules/gallery/views/form_uploadify.html.php

@@ -131,7 +131,7 @@
 
     <? if (identity::active_user()->admin && !$movies_allowed): ?>
     <p class="g-warning">
-      <?= t("Can't find <i>ffmpeg</i> on your system. Movie uploading disabled. <a href=\"%help_url\">Help!</a>", array("help_url" => "http://codex.galleryproject.org/Gallery3:FAQ#Why_does_it_say_I.27m_missing_ffmpeg.3F")) ?>
+      <?= t("Movie uploading is disabled on your system. <a href=\"%help_url\">Help!</a>", array("help_url" => url::site("admin/movies"))) ?>
     </p>
     <? endif ?>
   </div>