update code to reflect the new minimum python version 3.7

- update string format method
- remove redundant default arguments from function  calls
- remove unused imports
- remove unicode identifier from strings, it's default in py3 (see: https://stackoverflow.com/a/4182635/12201331)

allianceauth/authentication/migrations/0001_initial.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2016-09-05 21:38
-from __future__ import unicode_literals
 
 from django.conf import settings
 from django.db import migrations, models

allianceauth/authentication/migrations/0002_auto_20160907_1914.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2016-09-07 19:14
-from __future__ import unicode_literals
 
 from django.db import migrations
 

allianceauth/authentication/migrations/0003_authservicesinfo_state.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2016-09-09 20:29
-from __future__ import unicode_literals
 
 from django.db import migrations, models
 

allianceauth/authentication/migrations/0004_create_permissions.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2016-09-09 23:19
-from __future__ import unicode_literals
 
 from django.db import migrations
 

allianceauth/authentication/migrations/0005_delete_perms.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2016-09-09 23:11
-from __future__ import unicode_literals
 
 from django.db import migrations
 

allianceauth/authentication/migrations/0006_auto_20160910_0542.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2016-09-10 05:42
-from __future__ import unicode_literals
 
 from django.db import migrations
 

allianceauth/authentication/migrations/0007_remove_authservicesinfo_is_blue.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2016-09-10 21:50
-from __future__ import unicode_literals
 
 from django.db import migrations
 

allianceauth/authentication/migrations/0008_set_state.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2016-09-12 13:04
-from __future__ import unicode_literals
 
 from django.db import migrations
 

allianceauth/authentication/migrations/0009_auto_20161021_0228.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.2 on 2016-10-21 02:28
-from __future__ import unicode_literals
 
 from django.db import migrations, models
 

allianceauth/authentication/migrations/0010_only_one_authservicesinfo.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2017-01-07 06:47
-from __future__ import unicode_literals
 
 from django.db import migrations
 
@@ -9,7 +8,7 @@ def count_completed_fields(model):
 def forward(apps, schema_editor):
     # this ensures only one model exists per user
     AuthServicesInfo = apps.get_model('authentication', 'AuthServicesInfo')
-    users = set([a.user for a in AuthServicesInfo.objects.all()])
+    users = {a.user for a in AuthServicesInfo.objects.all()}
     for u in users:
         auths = AuthServicesInfo.objects.filter(user=u)
         if auths.count() > 1:

allianceauth/authentication/migrations/0011_authservicesinfo_user_onetoonefield.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2017-01-07 07:11
-from __future__ import unicode_literals
 
 from django.conf import settings
 from django.db import migrations, models

allianceauth/authentication/migrations/0012_remove_add_delete_authservicesinfo_permissions.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.5 on 2017-01-12 00:59
-from __future__ import unicode_literals
 
 from django.db import migrations, models
 

allianceauth/authentication/migrations/0013_service_modules.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.2 on 2016-12-11 23:14
-from __future__ import unicode_literals
 
 from django.db import migrations
 

allianceauth/authentication/migrations/0014_fleetup_permission.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.1 on 2016-09-09 23:19
-from __future__ import unicode_literals
 
 from django.db import migrations
 

allianceauth/authentication/migrations/0015_user_profiles.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.10.5 on 2017-03-22 23:09
-from __future__ import unicode_literals
 
 import allianceauth.authentication.models
 import django.db.models.deletion

allianceauth/authentication/migrations/0017_remove_fleetup_permission.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 from django.db import migrations