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 
In theory we want to catch everything that is raised here, so we can update the DB so we don't leave it in an inconsistent state. At the end I'm raising it again so it should not be a problem