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/ubuntu1604/Dockerfile

@@ -15,6 +15,7 @@ RUN apt-get update -y && \
     dpkg-dev \
     fakeroot \
     gawk \
+    gcc \
     git \
     iproute2 \
     libffi-dev \
@@ -27,7 +28,8 @@ RUN apt-get update -y && \
     mysql-server \
     openssh-client \
     openssh-server \
-    python-coverage \
+    python-cryptography \
+    python-dev \
     python-dbus \
     python-httplib2 \
     python-jinja2 \
@@ -64,6 +66,6 @@ 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 coverage junit-xml
 ENV container=docker
 CMD ["/sbin/init"]