Fix #1025 -- Python 3.7 support (#1245)

* Fix #1025 -- Python 3.7 support

* Upgrade redis-py

* Travis: xenial

* Fix version specifier

src/setup.py

@@ -104,8 +104,8 @@ setup(
         'django-otp==0.4.*',
         'python-u2flib-server==4.*',
         'django-formtools==2.1',
-        'celery>=4.1.1,<4.2.0',
-        'kombu==4.2.*',
+        'celery==4.3.*',
+        'kombu==4.5.*',
         'django-statici18n==1.8.*',
         'inlinestyler==0.2.*',
         'BeautifulSoup4==4.7.*',
@@ -121,8 +121,8 @@ setup(
         'babel',
         'paypalrestsdk==1.13.*',
         'pycparser==2.13',
-        'django-redis==4.8.*',
-        'redis==2.10.5',
+        'django-redis==4.10.*',
+        'redis==3.2.*',
         'stripe==2.0.*',
         'chardet<3.1.0,>=3.0.2',
         'mt-940==3.2',