`**` rules for `py` files in `mail` and `sms` were not working as expected: they
only matched files directly inside the folder, without any depth. Indeed
`gitignore` syntax specifies that a slash must follow the double asterisks.
Doc: https://git-scm.com/docs/gitignore#_pattern_format
Added `rd-sm` to the various mail test folders, and removed `rd-discuss` from
`test_mass_mailing` specifically.
Specified which files are to be observed in `tools` for `rd-images`, as it would
otherwise generate too much noise.
closesodoo/odoo#51019
Signed-off-by: Olivier Dony (odo) <odo@openerp.com>