Compute: drive NW configuration via software conf

This example extends the compute software configuration
so that heat metadata is used to model the os-net-config
YAML (ultimately JSON) directly. The existing
os-net-config element already supports this format.

Configuring the physical network layer in this manner
would supplant the ever growing list of Heat parameters
that we have and is something that could be automatically
generated via tuskar.

The default is to use net-config-noop.yaml which
will pass no config metadata into the os-net-config
element which will essentially disable it in favor
of using parameters w/ init-neutron-ovs.

Change-Id: I30f325b1751caaef5624537e63ee27c2e418d5c8

net-config-bridge.yaml

@@ -0,0 +1,37 @@
+heat_template_version: 2014-10-16
+
+description: >
+  Software Config to drive os-net-config for a simple bridge.
+
+resources:
+  OsNetConfigImpl:
+    type: OS::Heat::StructuredConfig
+    properties:
+      group: os-apply-config
+      config:
+        os_net_config:
+          network_config:
+            -
+              type: ovs_bridge
+              name: {get_input: bridge_name}
+              use_dhcp: true
+              # Can't do this yet: https://bugs.launchpad.net/heat/+bug/1344284
+              #ovs_extra:
+              #  - list_join:
+              #    - ' '
+              #    - - br-set-external-id
+              #      - {get_input: bridge_name}
+              #      - bridge-id
+              #      - {get_input: bridge_name}
+              members:
+                -
+                  type: interface
+                  name: {get_input: interface_name}
+                  # force the MAC address of the bridge to this interface
+                  primary: true
+
+outputs:
+  config_id:
+    description: The ID of the OsNetConfigImpl resource.
+    value:
+      {get_resource: OsNetConfigImpl}