only generate one clientmanager instance in interactive mode

Currently, we repeated to generate clientmanager instance when run
command in interactive mode. This should be avoided.

Change-Id: I0536a690bc173be38af08a2e4443115532041efd
Closes-Bug: #1383083
Clean up shell authentication

* Remove the auth option checks as the auth plugins will validate
  their own options
* Move the initialization of client_manager to the end of
  initialize_app() so it is always called.  Note that no attempts
  to actually authenticate occur until the first use of one of the
  client attributes in client_manager.  This leaves
  initialize_clientmanager() (formerly uathenticate_user()) empty
  so remove it.
* Remove interact() as the client_manager has already been created
  And there is nothing left.
* prepare_to_run_command() is reduced to trigger an authentication
  attempt for the best_effort auth commands, currently the only
  one is 'complete'.
* Add prompt_for_password() to ask the user to enter a password
  when necessary.  Passed to ClientManager in a new kward pw_func.

Change-Id: I9fdec9144c4c84f65aed1cf91ce41fe1895089b2
Begin low-level API for Network v2

api.network.APIv2 starts with network_list() support to flwsh out
the skeleton of the Network API.

Change-Id: I9a2b90cde84eced1f2ea6a014b769e2bae668211
Merge branch 'object-test-open' into dt-test
Merge branch 'examples' into dt-test
Merge branch 'fix-token-issue' into dt-test
Merge branch 'low-level-api-network' into dt-test