ganeti.initd: Add “status” action

Eric Rostetter sent a patch adding a “status” action, but unfortunately
his code was apparently specific to Red Hat. I hope this implementation
is more distribution-agnostic; after all “status_of_proc” is part of
LSB. Example output:

$ /etc/init.d/ganeti status
ganeti-noded is not running ... failed!
ganeti-masterd is running.
ganeti-rapi is running.
ganeti-confd is running.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>