Bug 6874: id based on contents, filename, and directory.

Bug 6874: id based on contents, filename, and directory.

This patch corrects the inability to upload the same file to a
different directory, or even a renamed file to the same
directory. By including the filename and directory as part of
the $id SHA generation, only identical files in the same
directory with the same file name will generate the same $id.

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@unc.edu.ar>