fix libsodium issue (#432)

Author: dcrankshaw

dockerfiles/ClipperTestsDockerfile

@@ -15,9 +15,12 @@ RUN echo 'export PATH=/opt/conda/bin:$PATH' > /etc/profile.d/conda.sh \
     && /bin/bash /tmp/anaconda.sh -b -p /opt/conda \
     && rm /tmp/anaconda.sh
 ENV PATH "/opt/conda/bin:$PATH"
-RUN conda install -y libgcc pyzmq
+RUN conda config --set ssl_verify no \
+    && conda install -c anaconda cloudpickle=0.5.2 \
+    && conda install -y libgcc pyzmq libsodium
 
-RUN pip install requests subprocess32 scikit-learn numpy pyyaml docker kubernetes pyspark tensorflow cloudpickle==0.5.2
+RUN pip install requests subprocess32 scikit-learn numpy pyyaml docker kubernetes tensorflow
+RUN conda install pyspark
 
 # Install maven
 ARG MAVEN_VERSION=3.5.0