CORD-828, Force upgrade the requests package

Change-Id: Ib84ba1026458797822e2ba2b84652e6f4e0d687c
diff --git a/containers/xos/Dockerfile.base b/containers/xos/Dockerfile.base
index e6ffc2a..d3a5483 100644
--- a/containers/xos/Dockerfile.base
+++ b/containers/xos/Dockerfile.base
@@ -44,7 +44,9 @@
 # Install python packages with pip
 COPY pip_requirements.txt /tmp/pip_requirements.txt
 
-RUN pip install --no-deps -r /tmp/pip_requirements.txt \
+# Upgrade requests from apt installed version
+RUN pip install --no-deps -U -I requests==2.11.1 \
+ && pip install --no-deps -r /tmp/pip_requirements.txt \
  && pip freeze > /var/xos/pip_freeze_pip_up_`date -u +%Y%m%dT%H%M%S`
 
 # Copy over ansible hosts