Add widget support to SourceColumn

Allow passing a widget class to SourceColumn. This makes
using lambdas to render model column unnecesary and are
mostly removed too.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

mayan/apps/django_gpg/apps.py

@@ -44,22 +44,24 @@ class DjangoGPGApp(MayanAppConfig):
             )
         )
 
-        SourceColumn(source=Key, label=_('Key ID'), attribute='key_id')
-        SourceColumn(source=Key, label=_('User ID'), attribute='user_id')
+        SourceColumn(attribute='key_id', is_identifier=True, source=Key)
+        SourceColumn(attribute='user_id', source=Key)
 
-        SourceColumn(source=KeyStub, label=_('Key ID'), attribute='key_id')
-        SourceColumn(source=KeyStub, label=_('Type'), attribute='key_type')
         SourceColumn(
-            source=KeyStub, label=_('Creation date'), attribute='date'
+            attribute='key_id.fget', is_identifier=True, source=KeyStub
+        )
+        SourceColumn(attribute='key_type', label=_('Type'), source=KeyStub)
+        SourceColumn(
+            attribute='date', label=_('Creation date'), source=KeyStub
         )
         SourceColumn(
-            source=KeyStub, label=_('Expiration date'),
-            func=lambda context: context['object'].expires or _('No expiration')
+            attribute='expires', empty_value=_('No expiration'),
+            label=_('Expiration date'), source=KeyStub
         )
-        SourceColumn(source=KeyStub, label=_('Length'), attribute='length')
+        SourceColumn(attribute='length', label=_('Length'), source=KeyStub)
         SourceColumn(
-            source=KeyStub, label=_('User ID'),
-            func=lambda context: ', '.join(context['object'].user_id)
+            func=lambda context: ', '.join(context['object'].user_id),
+            label=_('User ID'), source=KeyStub
         )
 
         menu_object.bind_links(links=(link_key_detail,), sources=(Key,))

mayan/apps/django_gpg/classes.py

@@ -6,6 +6,8 @@ import shutil
 
 import gnupg
 
+from django.utils.translation import ugettext_lazy as _
+
 from mayan.apps.common.utils import mkdtemp
 
 
@@ -149,6 +151,7 @@ class KeyStub(object):
     @property
     def key_id(self):
         return self.fingerprint[-8:]
+    key_id.fget.short_description = _('Key ID')
 
 
 class SignatureVerification(object):

mayan/apps/django_gpg/models.py

@@ -85,6 +85,7 @@ class Key(models.Model):
         Short form key ID (using the first 8 characters).
         """
         return self.fingerprint[-8:]
+    key_id.fget.short_description = _('Key ID')
 
     def save(self, *args, **kwargs):
         import_results, key_info = gpg_backend.import_and_list_keys(