Raw data status filepath removal

Modifications to the raw data object:
 - Added a status to the raw data, to know when the files have been uploaded or they are being uploaded.
 - Added a function to remove all the filepaths associated from the RawData `clear_filepaths`
 - Added a function to remove a filepath from the RawData `remove_filepath`

Adds the needed bits for #548 
This block should probably test whether or not the files exist because if they don't rmtree would fail, note that this can only happen if there are inconsistencies between the filesystem and the DB, while we don't anticipate having them I think it's good to be prepared for this.