Adding centos 6 to the travis mix

.travis.yml

@@ -14,6 +14,7 @@ matrix:
       python: 3.4
     - env: TARGET=sanity TOXENV=py35
       python: 3.5
+    - env: TARGET=centos6
     - env: TARGET=centos7 TARGET_OPTIONS="--volume=/sys/fs/cgroup:/sys/fs/cgroup:ro"
     - env: TARGET=fedora23 TARGET_OPTIONS="--volume=/sys/fs/cgroup:/sys/fs/cgroup:ro"
     - env: TARGET=ubuntu1404

test/utils/docker/centos6/Dockerfile

@@ -0,0 +1,33 @@
+# Latest version of centos
+FROM centos:centos6
+RUN yum -y update; yum clean all; 
+RUN yum -y install \
+    epel-release \
+    file \
+    git \
+    make \
+    mercurial \
+    rubygems \
+    sed \
+    subversion \
+    sudo \
+    unzip \
+    which
+RUN yum -y install \
+    PyYAML \
+    python-coverage \
+    python-httplib2 \
+    python-jinja2 \
+    python-keyczar \
+    python-mock \
+    python-nose \
+    python-paramiko \
+    python-pip \
+    python-setuptools \
+    python-virtualenv
+RUN /bin/sed -i -e 's/^\(Defaults\s*requiretty\)/#--- \1/'  /etc/sudoers
+RUN mkdir /etc/ansible/
+RUN /bin/echo -e '[local]\nlocalhost ansible_connection=local' > /etc/ansible/hosts
+#VOLUME /sys/fs/cgroup /run /tmp
+ENV container=docker
+CMD ["/sbin/init"]