Revert "usar checksum en lugar de _id donde corresponda en templates"

This reverts commit 837f4fc51a2073ee6843cc9615f10f0cc8eadf04.
Revert "Media: agregar campo checksum"

This reverts commit 6954adee00ac0f5f80ffec5fbd2ac6ab4108ef01.
Merge pull request #64 from inaes-tic/crear/revert-to-id

Crear/revert-to-id