Add a Nova Flavor resource.

This will allow using more fine-grained specification of computational
resources (RAM, CPU, disk, etc.).

A nova flavor resource has the following format:

  heat_template_version: 2013-05-23
  description:  Heat Flavor creation example
    resources:
      test_flavor:
        type: OS::Nova::Flavor
        properties:
          ram: 1024
          vcpus: 1
          disk: 20
          swap: 2

Change-Id: I79812f0ef0d0dc616ccb3361e9b5864faa877df1
Implements: blueprint dynamic-flavors
Merge "Add a Nova Flavor resource."