NCBC-341: AOOR when deserializing bootstrap config with empty 'pools' element

Change-Id: I38f77a6d02a80e619d9ab4f0197847ae4bca68e7
Reviewed-on: http://review.couchbase.org/30858
Reviewed-by: Jeffry Morris <jeffrymorris@gmail.com>
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>