rax_clb module: Ensure the id attribute is returned for a node

Currently, when rax_clb returns a list of nodes after an execution for use with register, the nodes are lacking the 'id' attribute.  This is due to the `to_dict` method of the node in pyrax, not including it.  This has been fixed in pyrax, but as a backwards compatible fix for ansible, this pull request ensures that the id attribute is returned.