RDR-1074 file cde handling was not checking the "-clear" flag flag used by Django to signal delete: Behaviour is:
RDR-1074 file cde handling was not checking the "-clear" flag flag used by Django to signal delete:
Behaviour is:

if file uploaded, then file is read into gridfs deleting any existing file

if the clear flag is "on" - the existing file is deleted
( NB the flag in post data is field <file cde code>-clear

if a file has been uploaded but no change is made to that file ( another field may have been edited ) - the existing file wrapper is retrieved and the gridfs_dict saved to mongo

muccg/rdrf,muccg/rdrf,muccg/rdrf,muccg/rdrf,muccg/rdrf