Make installation of EPEL optional (#1721)

roles/kubernetes/preinstall/defaults/main.yml

@@ -5,6 +5,7 @@ run_gitinfos: false
 ignore_assert_errors: false
 
 epel_rpm_download_url: "https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm"
+epel_enabled: true
 
 common_required_pkgs:
   - python-httplib2

roles/kubernetes/preinstall/tasks/main.yml

@@ -114,6 +114,7 @@
     - ansible_distribution in ["CentOS","RedHat"]
     - not is_atomic
     - epel_rpm_download_url != ''
+    - epel_enabled|bool
   register: epel_task_result
   until: epel_task_result|succeeded
   retries: 4