Update pillow from 3.4.2 to 4.1.0

Author: pyup-bot

project/requirements/base.txt

@@ -18,7 +18,7 @@ django-floppyforms==1.7.0
 django-model-utils==3.0.0
 
 # Images
-Pillow==3.4.2
+Pillow==4.1.0
 
 # Python-PostgreSQL Database Adapter
 psycopg2==2.6.2