urpmi-proxy TODO:
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 - fix sending 304 not modified when requested!
 - check unmodified for FTP
 - fix chosen mirrorlist better
 - fix rsync
 - delete old rpm versions (or another way to keep cache small)
 - better config system
 - default extension based mime type checking
 - using progress for size checking (configurable)
 - using buffered data for mime type checking (configurable)
 - check for a better apache.conf system to be used in webapps.d/