[ADD] add `project_timesheet_funding_wish` addon

adds in the timesheet lines:
- ``funding wish`` field: user tells if we want to be paid for the
time spent
- ``treated`` field: tells if the timesheet line has been considered
in internal invoicing process

Task: JOI-13

project_timesheet_funding_wish/__init__.py

@@ -0,0 +1,3 @@
+# -*- coding: utf-8 -*-
+
+from . import models