Release 0.2.0

Backwards-incompatible changes

• The non-standard parameter networks in the create_node driver
  method has been renamed to ex_networks, in order to signal that
  it's non-standard.

Backwards-compatible changes

• New driver method ex_list_networks() which returns a list of
  defined networks.

Bug fixes

• The driver method deploy_node() was badly broken:
  • It did not work if the node had not been created before.
  • It did not return the node object for the created node.