Support for external metadata in Dataset browser.

In order to provide extensible support for other datasources in the dataset browser (e.g., HDFS) it would be great to support external metadata describing that dataset (or datasets).
The interaction could then look as follows:
a) user point dataset browser to a specific configuration file e.g., hdfs://data/beakerxconfig.json.
b) the datasets configured in that list automatically can be selected/viewed from the dataset browser.

P.S. We are more than happy to contribute a more formal design doc if this is of interest to other users as well.