tosca floating ip support

sridhar_ram (03/24/2017): I would suggest to add something like to,

  tosca.nodes.network.Port:
    derived_from: tosca.nodes.Root
    properties:
      ip_address:
        type: string
        required: false
      floating_ip:
        type: map
        required: false

    map of { ip_address, public_network }