Previously if a DataStore would be embedded as a TerminaterDataStore inside
a LimitedStore. This makes additional interfaces, such as GetReaderDataStore,
inaccessible since we are not able to cast a LimitedStore to
GetReaderDataStore. The solution was to manually expose the specific methods
although this is definitly not the nicest solution.
This fix is in limitedstore/limitedstore.go, to intelligently terminate
existing file uploads. The store.uploads map is sorted, and
then analysed to remove the bigger existing uploads first.