Potential ARD mocking updates

[ddsjoberg]

1. Add a function that will allow users to update how the X's appear in the tables, e.g. "xx.x" or "xx.xx" or "xxx".
2. We can add an additional class to these mock tables, and we could then write a function that could convert the mock ARD into the code needed to create that ARD based on real data. This will be much more complex of a task if ARDs have already been stacked.
3. Add functions mock_hierarchical() and mock_stack()