MB-23327 Don't crash when building example service spec.
MB-23327 Don't crash when building example service spec.

In case node uuid is missing from the config, which may happen during
node rename. Handling this in a more principled way is unfortunately
is not that easy.

Change-Id: I6daf1993fc26820391e988e38b2f4cf4b6e7fd6d
Reviewed-on: http://review.couchbase.org/75505
Tested-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Well-Formed: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Dave Finlay <7b10a9ed9f70e64c30b07607a671ae61c33f14c8@couchbase.com>

membase/ns_server,membase/ns_server,ceejatec/ns_server,ceejatec/ns_server,ceejatec/ns_server,ceejatec/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,membase/ns_server