add cryptography python package to avoid warning Srikanth found

Change-Id: Ia62293126220df0654d6d2d811cb8de1b31d42a3
diff --git a/containers/xos/Dockerfile.base b/containers/xos/Dockerfile.base
index 294d972..578f417 100644
--- a/containers/xos/Dockerfile.base
+++ b/containers/xos/Dockerfile.base
@@ -36,6 +36,7 @@
 RUN pip install \
     ansible \
     ca-certs-locater \
+    cryptography \
     "django>=1.8,<1.8.99" \
     django-bitfield \
     django-crispy-forms \