Add oslo_service package to heat

Delorean repo has latests version of heat, which requires oslo_service,
but there is no oslo_service rpm package upstream yet. This has to be
pip installed until packaging problem is solved in repo.

Change-Id: Id147dde9dc7cbe5b734fbf4671d48a0404a1548b
Closes-Bug: #1469001

docker/centos/binary/heat/heat-base/Dockerfile

 FROM %%KOLLA_NAMESPACE%%/%%KOLLA_PREFIX%%base:%%KOLLA_TAG%%
 MAINTAINER Kolla Project (https://launchpad.net/kolla)
 
+# TODO(inc0): when oslo_service lands in delorean, change pip to yum
 # necessary until https://bugzilla.redhat.com/show_bug.cgi?id=1229477 is fixed
-RUN yum -y install python-oslo-policy && yum clean all
+RUN yum -y install python-oslo-policy && yum clean all && pip install oslo.service
 
 RUN mkdir -p /opt/kolla
 COPY config-heat.sh /opt/kolla/config-heat.sh