Add sale_condition_template

I moved this module from sale-workflow.  Displaying additional condition texts on sales reports is clearly a reporting module.

This module has been migrated from sale_condition_text, here is the original PR for the migration before I moved the module: https://github.com/OCA/sale-workflow/pull/50

This is still a WIP module because the report does not show the fields at the moment.

Depends on :

 * [ ] https://github.com/OCA/account-invoice-reporting/pull/14
 * [ ] https://github.com/OCA/account-invoice-reporting/pull/15
Adopted the @yvaucher's proposal