Should not show 'Send a file' menu when file transfer is disabled
When file transfers are disabled for Spark clients via Client Control plugin in Admin Console, after relogin Spark will not show a file transfer button in the chat window. But it still shows the 'Send a file' context menu entry when you right click a contact in the roster. It also lets you pick a file, but the transfer is not happening. So it is a visual issue only.
Hide "Send a file" menu entry when File transfer is disabled.