[FIX] encoded some stirng with utf-8 which could not be converted into ascii
[FIX] report: force encoding of dateformat string

some locales have unicode into the date format (eg: zh_CN uses %Y年%m月%d日)
conversion using str() would not work for them
opw #593932
[FIX] ir.model: during creation of custom models, the _auto_init call should also take care of custom fields created on-the-fly

The _auto_init call in ir.model.fields creation will not
do it because it happens before the insertion of the model
in the registry. It will only work for later addition of
fields.