rpm: make dependencies of zookeeper and fuse packages optional

Current "make rpm" requires zookeeper-lib-devel and fuse-devel
unconditionally. When users don't want zookeeper driver or sheepfs,
they should be disabled.

Related issue:
https://bugs.launchpad.net/sheepdog-project/+bug/1264253

Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: Liu Yuan <namei.unix@gmail.com>
deb: create deb package from raw source archive

This patch makes it possible for users to create debian package from
raw source archive.

Related issue:
https://bugs.launchpad.net/sheepdog-project/+bug/1264255

Reported-by: Bastian Scholz <scholzb@t-online.de>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: Liu Yuan <namei.unix@gmail.com>