7.0 Conversion_dict is now created in the generic parser

The conversion dict is displaced from the file_parser to the generic_parser in order to avoid the error of the validate function when creating a new parser which does not contain the 4 basc fields (ref, amount, date, label)

The old launchpad link : 
https://code.launchpad.net/~akretion-team/banking-addons/account_statement_base_import_conversion_dict/+merge/198235
better to import
```
from openerp.tools import ustr
```
It may be the same function, but openerp.tools seems safer and makes more sense