Docker image updates for integration tests. (#26054)

* Sort packages to install.
* Add python-argparse to centos6 docker image.
* Add gcc and python dev lib to docker images.
* Add python cryptography to docker images.
* Add coverage using pip instead of OS packages.
* Update old pip versions in docker images.
* Exclude */pyshared/* from coverage reporting.

test/utils/docker/ubuntu1204/Dockerfile

@@ -26,7 +26,6 @@ RUN apt-get update -y && \
     mysql-server \
     openssh-client \
     openssh-server \
-    python-coverage \
     python-dev \
     python-httplib2 \
     python-jinja2 \
@@ -55,6 +54,7 @@ RUN apt-get update -y && \
     apt-get clean
 
 RUN pip install --upgrade pycrypto cryptography
+
 # helpful things taken from the ubuntu-upstart Dockerfile:
 # https://github.com/tianon/dockerfiles/blob/4d24a12b54b75b3e0904d8a285900d88d3326361/sbin-init/ubuntu/upstart/14.04/Dockerfile
 ADD init-fake.conf /etc/init/fake-container-events.conf
@@ -91,6 +91,7 @@ RUN ssh-keygen -q -t rsa -N '' -f /root/.ssh/id_rsa && \
     cp /root/.ssh/id_rsa.pub /root/.ssh/authorized_keys && \
     for key in /etc/ssh/ssh_host_*_key.pub; do echo "localhost $(cat ${key})" >> /root/.ssh/known_hosts; done
 VOLUME /sys/fs/cgroup /run/lock /run /tmp
-RUN pip install junit-xml
+RUN pip install pip --upgrade
+RUN pip install coverage junit-xml
 ENV container=docker
 CMD ["/sbin/init"]