Upgrade checker adds OS support for Oracle Linux Server

[Mars-weka]

When running the checker on Oracle Linux, it will get the following error message:

CHECKING IF OS IS SUPPORTED ON BACKENDS

Traceback (most recent call last):
File "weka_upgrade_checker.py", line 2067, in
main()
File "weka_upgrade_checker.py", line 2057, in main
backend_host_checks(backend_hosts, ssh_bk_hosts,
File "weka_upgrade_checker.py", line 1813, in backend_host_checks
check_os_release(host_name, result, weka_version,
File "weka_upgrade_checker.py", line 1460, in check_os_release
if version not in supported_os[check_version]['backends_clients'][dict_info['ID']]:
KeyError: 'ol'

The workaround is to change ID="ol" value to a supported os version on /etc/os-release file
e.g. sed -i s/ID=\"centos\"/ID=\"rhel\"/g /etc/os-release