./tests/run.py can't be used against the hp cloud

[Vincent Ladeuil]

Traceback (most recent call last):
  File "./tests/run.py", line 541, in <module>
    sys.exit(main())
  File "./tests/run.py", line 509, in main
    if needs_bootstrap():
  File "./tests/run.py", line 217, in needs_bootstrap
    get_bootstrap_ip(instance, 1)
  File "./tests/run.py", line 354, in get_bootstrap_ip
    raise Exception('Timed out waiting for bootstrap IP.')

This calls:
         net = server.networks.get('canonistack')

so we need the network name used in the targeted cloud to be configurable.