download file

This version introduces multiple enhancements:

possibility to download file

Details of additions/deletions below:
--------------------------------------------------------------

Modified:   lib/FileHandler.php
            -- Added --
                downloadAction allow to download file

Modified:   lib/FileList.phpgetFilesList
            -- Updated --
                added url encodedc file name to list

Modified:   skin/templates/file_list.php
            -- Updated --
                changed structure for download button