Some updates

Apparently repo.maven.apache.org has its HTTP access blocked, so I changed them to central.maven.org which appear to work well.

This introduced a new issue, which was that FML apparently assumed that the E-Tag was the file MD5, which is not the case for central.maven.org, so I modified the fml.py file so that it gives priority to .md5 files (which we can be sure they have to be the .md5 file), and if that fails, then it attempts to fetch the E-Tag.

I have also updated the server MD5 to the one currently available on Mojang's server.