New API Endpoint with DAX Queries

I finally got this partially worked out with the help of one of the very helpful Power BI engineers.  For some reason datasets in My Workspace don't seem to be getting proper build permissions, so I decided to switch to just testing datasets in my v2 workspaces.  

I initally thought that I had to use the format https://api.powerbi.com/v1.0/myorg/groups/{groupId}/datasets/{datasetId} because that is what I'm accustomed to doing.  This will probably change as this gets closer to GA, but for now you actually just remove the parts about the group and reference the dataset directly.  For example: https://api.powerbi.com/v1.0/myorg/datasets/f388a618-2c93-41c5-8528-44c0c1129d70/executeQueries

Once I made that change, I was able to return data from a Powershell script and Postman.  Still not sure about the permssions in My Workspace, but I'll likely never use that anway.