Revert the add of the helpdesk contact name, we use the existent

__init__.py

@@ -5,7 +5,6 @@ from .work import *
 
 def register():
     Pool.register(
-        Activity,
         Work,
         WorkType,
         module='project_helpdesk', type_='model')

view/activity_helpdesk_tree.xml

@@ -4,7 +4,7 @@ this repository contains the full copyright notices and license terms. -->
 <tree string="activity" editable="top">
     <field name="type"/>
     <field name="direction"/>
-    <field name="helpdesk_contact_name"/>
+    <field name="contact_name"/>
     <field name="subject"/>
     <field name="description"/>
 </tree>

view/work_helpdesk_form.xml

@@ -46,8 +46,8 @@ this repository contains the full copyright notices and license terms. -->
             <field name="last_action_date"/>
             <label name="channel"/>
             <field name="channel"/>
-            <label name="helpdesk_contact_name"/>
-            <field name="helpdesk_contact_name"/>
+            <label name="contact_name"/>
+            <field name="contact_name"/>
             <field name="activities" colspan="4" view_ids="project_helpdesk.activity_helpdesk_tree_view"/>
         </page>
         <page string="Allocations" id="allocations"

work.py

@@ -5,7 +5,7 @@ from trytond.pool import Pool, PoolMeta
 from trytond.pyson import Eval, If, And
 from trytond.transaction import Transaction
 
-__all__ = ['Work', 'WorkType', 'Activity']
+__all__ = ['Work', 'WorkType']
 __metaclass__ = PoolMeta
 
 
@@ -28,7 +28,6 @@ class Work:
             'required': And(Eval('type') == 'project', Eval('helpdesk', False)),
             'invisible': Eval('type') != 'project',
             }, depends=['type', 'helpdesk'])
-    helpdesk_contact_name = fields.Function(fields.Char('Contact Name'), 'get_helpdesk_contact')
 
     @staticmethod
     def default_helpdesk():
@@ -92,17 +91,3 @@ class Work:
         for work in works:
             work.check_helpdesk_project_creation()
             work.check_helpdesk_task_creation()
-
-    def get_helpdesk_contact(self, name=None):
-        if not self.activities:
-            return None
-        Activity = Pool().get('activity.activity')
-        act = Activity.search([('resource', '=', 'project.work,%s' %
-            self.id)], order=[('dtstart', 'desc')], limit=1)
-        return act and act[0].helpdesk_contact_name or None
-
-
-class Activity:
-    __name__ = 'activity.activity'
-
-    helpdesk_contact_name = fields.Char('Helpdesk Contact Name')