Install libnss-unknown2 pacakge at the end

We need to do this because the libnss-unknown package switches the uids, which creates problems for system pacakges that create users/groups during installation.

Eventually, we would like to fix this issue proper. Until then, this is a workaround to defer the libnss-unknown package's installation to the last.

Note: Also rename pacakge to libnss-unknown

Signed-off-by: Ritesh Raj Sarraf ritesh.sarraf@collabora.com