Node template does not inherit node type interfaces directly

Node templates are not inheriting node type interfaces, but include include node type definition

Example:

###### Node type

  tosca.openstack.authorization_form:
    derived_from: tosca.openstack.node
    properties:
      username:
        type: string
        required: true
      password:
        type: string
        required: true
      tenant_name:
        type: string
        required: true
      auth_url:
        type: string
        required: true
      region:
        type: string
        required: true
    attributes:
      auth_token:
        type: string
    interfaces:
      Standard:
        type: tosca.interfaces.node.lifecycle.Standard
        create:
          implementation: openstack_plugin.keystone.authorize
          inputs:
            args:
              type: list
            kwargs:
              type: map

######## Node template

    authorization_form:
      type: tosca.openstack.authorization_form
      properties:
        username: { get_input: keystone_username }
        password: { get_input: keystone_password }
        tenant_name: { get_input: keystone_tenant_name }
        auth_url: { get_input: keystone_url }
        region: { get_input: openstack_region }

So, when parser will return number of nodes through TOSCA graph node template interfaces will have an empty list, but its node type has explicitly defined interfaces. Inheritance is broken.