Avoid pip upgrades during Docker builds

Dockerfile

@@ -28,13 +28,13 @@ RUN chmod +x /usr/bin/celery-cmd
 # RUN cd /usr/src/geonode-contribs/geonode-logstash; pip install --upgrade  -e . \
 #     cd /usr/src/geonode-contribs/ldap; pip install --upgrade  -e .
 
-RUN yes w | pip install --src /usr/src -Ur requirements.txt
-RUN yes w | pip install --upgrade -e .
+RUN yes w | pip install --src /usr/src -r requirements.txt &&\
+    yes w | pip install -e .
 
 # Cleanup apt update lists
-RUN apt-get autoremove --purge
-RUN apt-get clean
-RUN rm -rf /var/lib/apt/lists/*
+RUN apt-get autoremove --purge &&\
+    apt-get clean &&\
+    rm -rf /var/lib/apt/lists/*
 
 # Export ports
 EXPOSE 8000