update dependencies

requirements.txt

@@ -1,15 +1,12 @@
 gunicorn>=19.6.0
-Django>=1.10.3,<2.0
-wagtail>=1.5.3,<2.0
-django-taggit>=0.18.3
+Django>=2.2.0
+wagtail>=2.4
 watchdog>=0.8.3
 psutil>=5.0.1
 pyyaml>=3.12
 dateutils>=0.6.6
 bleach>=1.4.3
-django-overextends>=0.4.2
-Pillow>=3.3.0
-django-modelcluster==2.0
+django-auth-ldap>=1.7.0
 django-honeypot>=0.5.0
 django-jet>=1.0.3
 mutagen>=1.37