[#31160] Remove uses of JRequest in com_user

Update of https://github.com/joomla/joomla-cms/pull/1495  which is out of sync with master. Other than that me and @Bakual had a chat and agreed it should use the raw filter for passwords (as was the case in JRequest) rather than a base64/string filter

http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31160&start=0