Ability to reuse Workflow Templates on same Proof

[#1]

Would be beneficial if Workflow templates could be added more than once to a Workflow for instance.

A default template where all options are setup so the user does not have to change any stage settings apart from the stage name, add some users to it and then choose the same template from the Add Template dropdown menu to add another stage.

Currently this doesn't work and reports that the template has already been added to the proof, even when deleting the stage added by the template and trying to add it again causes the same error.

So if you delete template stage from the workflow it should be removed from the proof.