[8.0] Help online: new features

This PR add new features on help online module:

- import and export pages
- autobackup before update
- own menu
- record rules
- french translation

Note: Travis fails due to flake 8 issues on modules web_easy_switch_company and web_export_view.
It's seem that in odoo, by convention, docstrings are quoted using double quotes (") and others string with single quote ('). It would be nice to try to stay consistent. ex:
``` python
class ExportHelpWizard(models.TransientModel):
    _name = "export.help.wizard"
    _description = 'Export Help Online'
...
    def _clean_href_urls(self, page_node, page_prefix, template_prefix):
        '''
            Remove host address for href urls
        '''
...
    @api.multi
    def export_help(self):
        """
        Export all Qweb views related to help online in a Odoo
        data XML file
        """
```
I know, it's a detail and I am not myself always consistent. .. :smile: