[IMP] test experience and documentation

addons/account/tests/__init__.py

addons/account_followup/tests/__init__.py

addons/base_action_rule/tests/__init__.py

addons/base_import/tests/__init__.py

addons/decimal_precision/tests/__init__.py

addons/email_template/tests/__init__.py

addons/gamification/tests/__init__.py

addons/hr_holidays/tests/__init__.py

addons/lunch/tests/__init__.py

addons/mail/tests/__init__.py

addons/mass_mailing/tests/__init__.py

addons/note/tests/__init__.py

addons/payment_adyen/tests/__init__.py

addons/payment_buckaroo/tests/__init__.py

addons/payment_ogone/tests/__init__.py

addons/payment_paypal/tests/__init__.py

addons/portal/tests/__init__.py

addons/portal_project/tests/__init__.py

addons/portal_project_issue/tests/__init__.py

addons/product/tests/__init__.py