Fixing epel-release bug on MapR cluster installation
Fixing epel-release bug on MapR cluster installation

When installing MapR into a cluster on CentOS 7, the plugin tries to
download epel release version 7-8 from the url http://download.
fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-8.noarch.rpm.
This release version is not available anymore and should be replaced
with epel-release-7-9 on the url rpm -i http://download.
fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-9.noarch.rpm
bug https://bugs.launchpad.net/sahara/+bug/1615761 is because 7-5，
why can not replace with yum install -y epel-release to solve the
problem permanently in /opt/stack/sahara/sahara/plugins/mapr/
resources/add_mapr_repo.sh(31).

Closes-Bug:#1657048

Change-Id: I7705be363e99f10472dbf0ea3bb189228cbaf65f

openstack/sahara,openstack/sahara,tellesnobrega/sahara,tellesnobrega/sahara