[IMP] Backport one feature from website: this feature allows to specify a file
path on the field tag fetching the right file instead of using the base64
encoded file in the field.

<field name="image" type="base64" file="base/static/img/main_partner-image.png" />
[MERGE] Extract the base64 encoded images from the xml files lp:~openerp-dev/openobject-addons/trunk-extracted_img-stw