more mobile options added

 - $mobile_theme : support mobile specific theme
 - $mobile_menu : for mobile specific menu
 - disable wikiwyg / section edit for mobile
fix for the conditional get

 * make etag depend on the pagename.
 * always set as static page for the raw action
 * add a missing $use_conditional_get param
support conditional get for do_raw() action
checkUpdated($time, $delay) method added

use checkUpdated() to check caches already updated