CRM-14229 Static call to non static method in Joomla

An old static call to JMenu  in civicrm.php throws a warning in current versions of PHP. This replaces it with the correct code from the Joomla API.
Merge pull request #18 from elinw/4.4

CRM-14229 Static call to non static method in Joomla
Merge remote-tracking branch 'upstream/4.4' into 4.4-master-2014-02-18-07-53-48