Reverting to psycopg2==2.6.1 due to pip installation issues

requirements.txt

@@ -11,7 +11,7 @@ natsort>=5.0.0
 ncclient==0.5.2
 netaddr==0.7.18
 paramiko==2.0.0
-psycopg2==2.6.2
+psycopg2==2.6.1
 py-gfm==0.1.3
 pycrypto==2.6.1
 sqlparse==0.1.19