Let's solve an old and repeatedly reported File Roller issue

[Ma Xiaojun]

The bug: ZIP archives with non-ASCII filenames cannot survive a
round-trip in File Roller (when p7zip is not installed)
https://bugs.launchpad.net/ubuntu/+source/file-roller/+bug/592109

The problem is caused by broken support of UTF-8 filenames in unzip:
http://www.info-zip.org/phpBB3/viewtopic.php?f=4&t=405

I don't this problem can be solved any time soon.

People generally install p7zip as a workaround. So I guess we may just
make it official. Let File Roller depends on p7zip so that the user
can always have better ZIP support.

Another issue with unzip is that it doesn't support new compression
method of ZIP like LZMA and PPMd:
http://www.info-zip.org/phpBB3/viewtopic.php?f=4&t=113

While p7zip at least has good support for LZMA method.