Make kolla-toolbox container build on CentOS bin

Ansible installs pytz from pip which is newer then then pytz in
RDO repositories.  As part of this process, it removes pytz
which corrupts the python installation in some way.  This causes
further pip usage to produce a backtrace causing the kolla-toolbox
container not to build.

Mixing pip and RPM is not good.

Change-Id: I413468641bad5476cfcba61cb0e2189c31f3d682
Closes-Bug: #1545215

docker/kolla-toolbox/Dockerfile.j2

@@ -16,7 +16,8 @@ RUN yum -y install \
         openssl-devel \
         python-devel \
         openssh-clients \
-    && yum clean all
+    && yum clean all \
+    && yum -y remove pytz
 
 {% elif base_distro in ['ubuntu', 'debian'] %}