Add a dynamic warning message to the OOo Calc import tool to remind user to re-upload the file. This is a know limitation of the current implementation. A bug report has been written for this.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@7602 20353a03-c40f-0410-a6d1-a30d3c3de9de