Implements SeaMicro VendorPassThru functionality

* Adds "set_node_vlan_id", "attach_volume", "set_boot_device" methods
* "set_node_vlan_id" sets untagged vlan id of the node NIC
* "attach_volume" attaches volume from the volume pool
* "set_boot_device" sets the boot device for the node

Change-Id: I8d86a9585d7e4f710d3505183cac455af685dfe0
Implements: blueprint seamicro-vendor-passthru-interface-implementation
Merge "Implements SeaMicro VendorPassThru functionality"