Allow using the serial number for defining the bus order

This syncs in the latests changes from the get_bus_order function in the
"barclamp" cookbook of the "deployer" barclamp.
Merge pull request #579 from rhafer/pull-req-release-pebbles-master-ead8713cdc2ce28d97bab36901b28238e32bb08e

Allow using the serial number of a node as an additional matching criteria for the bus_order [2/3]