Allow users to create their own custom workflows

[erinknight242]

Instead of only customizing the default workflows of "Messaging" and "API", allow the user to add or delete workflows, and name them whatever they please. Out of the box, it should still have our default workflows, but the user can delete or change them if they'd like.

There must always be a minimum of one workflow. If there is only one workflow, we don't need to show the screen to select it when creating a new contract, it can assume that is the one to create from.