fixes #1814 - converts sp_* attributes into a BMC interface class

this patch also includes the following

• added a new interfaces table, and STI objects to represent a NIC, BMC, Managed
  and a bootable interface.
• refactored DHCP/DNS orchestation code, so they can work on the
  interface objects and on the primary interface information that still
  reside in the hosts table.
• added basic UI for interface selection

this refactor also helps to simply refactoring the host object into
multiple objects.

this patch also fixes
fixes #1325 - BMC NIC should also create DNS entry
fixes #1813 - allow to support multiple NIC per host