install: move lsb distro stuff into module

We will use this elsewhere.

Signed-off-by: Sage Weil <sage@inktank.com>
mon: support upstart or sysvinit

Signed-off-by: Sage Weil <sage@inktank.com>
mds: support upstart or sysvinit

Signed-off-by: Sage Weil <sage@inktank.com>
osd: support upstart or sysvinit

Signed-off-by: Sage Weil <sage@inktank.com>
osd: add --zap-disk argument

Newer ceph-disk-prepare will not zap by default.  Let the ceph-deploy user
pass it down.

Signed-off-by: Sage Weil <sage@inktank.com>
README: document --zap-disk

Signed-off-by: Sage Weil <sage@inktank.com>
zapdisk: fix exception name

Signed-off-by: Sage Weil <sage@inktank.com>