Remove ftp from the required list of protocol handlers

java.net.URL specifies that the following protocols are guaranteed to exist on the search path :-

         http, https, ftp, file, and jar
     
ftp is a legacy protocol and has been superseded by protocols such as sftp for some time. We should consider removing ftp from this list to allow for this protocol handler to be dropped some time in the future.

Another motivation to removing ftp from the list is that it allows it to be removed from the smallest profile or base module. That will allow 75k (uncompressed) of classes to be moved to another module.