Remove dynamic HTML index support from FTP server

The days of browsers rendering HTML served-up via FTP are over, so remove this feature. This also removes all JavaScript support from the FTP server and that is a bit odd as it was one of the first Synchronet components for which I added JS support.

Removing this feature was pretty painless; much easier than adding it was. The main motivation was less cruft to port to the file base in the works. There should be no more references to 00index.html anywhere at this point. Bye bye cool feature, we'll miss you.