onnode: fix get_nodes_with_status()

onnode: fix get_nodes_with_status()

Setting IFS and looping though items with colons in them doesn't work.
Change this to read through the output line by line.  The header line
needs to be thrown away by throwing away everything up to the 1st
newline.

Keep stderr from the "ctdb status" command, otherwise debugging is
impossible.

On error, append any output from ctdb to onnode's error message.

Signed-off-by: Martin Schwenke <martin@meltin.net>