mime_type and content_type.
Choose only one variable for consistency. This patch avoid loosing
useful informations.
content_type name is preferred because it is the id of property on
ERP5 Documents.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@38474 20353a03-c40f-0410-a6d1-a30d3c3de9de