Preload more Datasets

[martingraf4]

We should preload more datasets. As some datasets are quite large we should implement a feature to only add a reference to a dataset and download it during runtime with no further action required from the user.

• The WDC training dataset and gold standard for large-scale product matching
• Alaska Benchmark for Big Data Integration tasks

After implementing #112

• Leipzig DB Group Datasets
• Magellan Data Repository

Also syntethic data sets would be interesting. Maybe with custom configuration?

• Febrl

[phpfs]

The datasets released as part of the SIGMOD contest today are included with v2.0.0.