Enable credential sharing for Connectors tools between workstations

[KOBoyle]

Currently, when sharing a workflow with a Python-based connector such as Google BigQuery, the credentials for the tool have to be reentered if the workflow is opened on a workstation different from where the workflow was created or by a different user on the same workstation. 

There is no need to re-authenticate when publishing a workflow to run by a Server schedule or on the Gallery. This functionality should be extended to sharing the workflow between workstations with the Python registry key enabled.