Update psycopg2 from 2.6.2 to 2.7.1

Author: pyup-bot

project/requirements/base.txt

@@ -21,7 +21,7 @@ django-model-utils==3.0.0
 Pillow==4.1.0
 
 # Python-PostgreSQL Database Adapter
-psycopg2==2.6.2
+psycopg2==2.7.1
 
 # Unicode slugification
 git+git://github.com/mozilla/unicode-slugify#egg=unicode-slugify==0.1.3-HEAD