Fixes #9 (Support use of the SMBIOS UUID as a node identifier)

The changes in this pull request modify the Hanlon Microkernel so that it reports its (SMBIOS) UUID, in addition to the old MAC-address-based hardware identifier that was previously reported, to Hanlon as part of it's checkin and registration requests. The old (MAC-address-based) hardware identifier is reported using the new `mac_id` parameter (instead of the old `hw_id` parameter) while the (SMBIOS) UUID value is reported using the new `uuid` parameter. The changes in this PR are necessary to enable the use of the (SMBIOS) UUID as the hardware identifier for the node in Hanlon (enabled by the changes in csc/Hanlon/#161), but Hanlon will work without these changes (it will just continue to use the old MAC-address-based field instead).