[Gzz] Canonical blocks

[Benja Fallenstein]

Hi,

we can now add canonicalized blocks into a repository:

   java gzz.mediaserver.AddToMediaserver -c DIR CT FILE

where DIR is the mediaserver directory, CT the MIME content type, and 
FILE the file to add. CT can be "guess"; then, we try to get the 
filename through the extension.

However, I cannot complete my task as set forth in TODO, because there 
is no gzz.client.Synch class and therefore no way to sync with the 
repository on himalia. So, I cannot even get the blocks, much less 
create new, canonicalized blocks from them, or anything.

I'll move my TODO task to "anybody", because I'm not able to complete it.

- Benja