rm IterDataPipe, consolidate into ExperimentDataset, add docs/www builds
#122
| Job | Run time |
|---|---|
| 16s | |
| 1m 55s | |
| 3m 56s | |
| 3m 27s | |
| 3m 24s | |
| 3m 39s | |
| 16m 37s |