Track lost samples from rarefaction

This should replace #329. Note that if you have an ipython cluster running you need to terminate and then reload after doing a pull.
If possible, it would be good to do this all at once. Something like:

```python
all_samples[foo] = all_samples[foo] - samples_to_remove
```

How to get to that depends on if `proc_data_id` is variant within a `Table`. The motivation is to reduce function calls and to leverage bulk set operations