Refactor register_model_columns into SourceColumn class

mayan/apps/events/models.py

@@ -4,13 +4,7 @@ from django.db import models
 from django.utils.encoding import python_2_unicode_compatible
 from django.utils.translation import ugettext_lazy as _
 
-from actstream.models import Action
-
-from common.utils import encapsulate
-from navigation.api import register_model_list_columns
-
 from .classes import Event
-from .widgets import event_type_link
 
 
 @python_2_unicode_compatible
@@ -25,17 +19,3 @@ class EventType(models.Model):
         verbose_name_plural = _('Event types')
 
 
-register_model_list_columns(Action, [
-    {
-        'name': _('Timestamp'),
-        'attribute': 'timestamp'
-    },
-    {
-        'name': _('Actor'),
-        'attribute': 'actor',
-    },
-    {
-        'name': _('Verb'),
-        'attribute': encapsulate(lambda entry: event_type_link(entry))
-    },
-])