Started implementation of #6, switched to a asynchronous implementation of the dataset callback

Signed-off-by: Marko Locher <marko@locher.at>
Updated Readme with the changes from abcd435

Signed-off-by: Marko Locher <marko@locher.at>
Merge pull request #9 from EOX-A/locherm_asynchronous_datasets

Asynchronously load datasets