po: add missing translations in de, fr, it, zh

po: add missing translations in de, fr, it, zh

There are missing translations for the new "Copy" menu item.

The following people provided them to me on IRC just in time for the
QEMU 2.8 release:

 * de_DE - Stefan Hajnoczi <[email protected]>
 * fr_FR - Laurent Vivier <[email protected]>
 * it    - Pino Toscano <[email protected]>
 * zh_CN - Fam Zheng <[email protected]>

[Removed spurious space in zh_CN "Copy" translation that Fam Zheng
pointed out.
--Stefan]

Reported-by: Kevin Wolf <[email protected]>
Signed-off-by: Stefan Hajnoczi <[email protected]>
Message-id: 20161214144713[email protected]
Cc: Fam Zheng <[email protected]>
Cc: Pino Toscano <[email protected]>
Cc: Laurent Vivier <[email protected]>
Signed-off-by: Stefan Hajnoczi <[email protected]>