[IMP] openerp/service/db.py: lint file
[IMP] new backup format.

The new backup format is a zip containing the sql dump of the
database and the filestore of this database.

Old backups can still be restored
[MERGE] db dump/restore zip-based format.
The new format uses plain text sql and includes the filestore.
The old pg_dump format is still supported for db restore.