* (bug 20720) moved userjs and sitejs to after core scripts and before all extension...

* (bug 20720) moved userjs and sitejs to after core scripts and before all extension code.
* removed setupSkinUserJs (not called anywhere) same functionality in getHeadScripts
* moved Skin::getHeadScripts() to outputPage::getHeadScripts()
** ( part of an effort to clean up scripts insertion to OutputPage )
** Standard skin was the only skin that implemented the getHeadScripts method. Has been merged into a skin::OutputPage method.