Allocated ip available as attr, plus get_bus_map proof of concept [2/2]

This pull request includes:
1. Setting the allocate ip address as an attribute on the Node
2. The first piece of the conduit calculation (get_bus_map) along with a
   custom AttribInstance that makes the bus map for a node publicly available.
These two components are the first to exercise setting a Jig attribute on a node and making a custom attribute that is set on a node.


 .../app/models/bus_order_attrib_instance.rb        |   40 ++++++++++++++++++++
 crowbar_framework/app/models/interface_map.rb      |   15 +++++++-
 crowbar_framework/app/models/network.rb            |    3 +-
 crowbar_framework/test/network_test_helper.rb      |   24 +++++++++---
 .../test/unit/bus_order_attrib_instance_test.rb    |   35 +++++++++++++++++
 .../test/unit/interface_map_model_test.rb          |   35 ++++++++++++++++-
 crowbar_framework/test/unit/network_model_test.rb  |   13 ++++++-
 7 files changed, 154 insertions(+), 11 deletions(-)

Crowbar-Pull-ID: 619186241d4e828e4b1bca58c144dc8a9442c5b7

Crowbar-Release: development