added Forbidden in dataset create error catching

[loveeklund-osttra]

Solves issues #84

[z3z1ma]

Thanks, good thinking. I am curious on what the exception trace looks like when the dataset both doesn't exist and you don't have permission to create it. Since at that point we hit the Forbiddenhandling code path and call .get_dataset. We could probably catch it and log something simple and direct on how the user can fix this by updating SA permissions or creating the dataset ahead of time. But its more of a nit. LGTM.