apt-mirror fix to download installer files

Here are the changes I had to make to be able to download complete Ubuntu repository with X86_64 installer (netboot) directory contents. The apt-mirror was also failing for in18n directory as some files with extensions xz needed to be downloaded - that is fixed as well. Pay attention to less than symbol "<"

root@dhcp2064-29:~# diff /usr/bin/apt-mirror /usr/bin/apt-mirror.ori
> 
423,430d451
<             add_url_to_download( $url . $_ . "/cnf/Commands-" . $arch . ".xz" );            
<             add_url_to_download( $url . $_ . "/installer-amd64/current/legacy-images/netboot/" . "boot.img.gz" );            
<             add_url_to_download( $url . $_ . "/installer-amd64/current/legacy-images/netboot/" . "ldlinux.c32" );            
<             add_url_to_download( $url . $_ . "/installer-amd64/current/legacy-images/netboot/" . "mini.iso" );            
<             add_url_to_download( $url . $_ . "/installer-amd64/current/legacy-images/netboot/" . "netboot.tar.gz" );            
<             add_url_to_download( $url . $_ . "/installer-amd64/current/legacy-images/netboot/" . "pxelinux.0" );            
<             add_url_to_download( $url . $_ . "/installer-amd64/current/legacy-images/netboot/ubuntu-installer/amd64/" . "initrd.gz" );            
<             add_url_to_download( $url . $_ . "/installer-amd64/current/legacy-images/netboot/ubuntu-installer/amd64/" . "linux" );            
466,467c487
<     #$uri =~ s/^([^@]+)?@?// if $uri =~ /@/;
<     $uri =~ s/^([^@]+)?@?// if (split '/',$uri)[0] =~ /@/;
---
>     $uri =~ s/^([^@]+)?@?// if $uri =~ /@/;
503c523
<                     if ( $filename =~ m{^$component/i18n/Translation-[^./]*\.(bz2|xz)$} )
---
>                     if ( $filename =~ m{^$component/i18n/Translation-[^./]*\.bz2$} )
1046d1065
<