Diverse Code Cleanups

*Code wurde PEP-8 gerecht formatiert
* Kleine Fehler die der PyCharm Inspector beanstandet wurden korrigiert

mahjong_ranking/forms.py

@@ -1,11 +1,11 @@
 # -*- encoding: utf-8 -*-
 
-'''
+"""
 Created on 04.10.2011
 
 @author: christian
-'''
-from django.contrib.auth.models import User
+"""
+from django.contrib.auth import get_user_model
 import django.forms
 from django.forms.models import BaseInlineFormSet, inlineformset_factory
 from django.utils import timezone
@@ -30,10 +30,10 @@ class HanchanForm(forms.ModelForm):
         }
 
     def clean_start(self):
-        u'''
+        u"""
         Das Datum darf nicht in der Zukunft liegen und es muss innerhalb der
         Dauer des Events liegen.
-        '''
+        """
         start = self.cleaned_data['start']
         event = self.cleaned_data['event']
         if start > timezone.now():
@@ -58,8 +58,8 @@ class HanchanAdminForm(HanchanForm):
 class PlayerForm(forms.ModelForm):
     error_css_class = 'error'
     required_css_class = 'required'
-    player_choices = User.objects.filter(groups__in=(1, 2)).distinct()
-    player_choices = player_choices.order_by('username')
+    player_choices = get_user_model().objects.filter(groups__in=(1, 2))
+    player_choices = player_choices.order_by('username').distinct()
     user = forms.ModelChoiceField(player_choices, required=True)
     comment = forms.CharField(
         widget=forms.widgets.TextInput(attrs={'maxlength': 255}),