[Fedora] Add package_installed OVAL templating functionality [Fedora] Include initial OVAL check if ntpd service is enabled

[Jan Lieskovsky]

[Fedora] Add package_installed OVAL templating directory structure and functionality
         (prerequisite for the service enabled checks)

[Fedora] Include initial OVAL check if ntpd service is enabled

This patch adds:
* possibility to create package_installed OVAL checks in automated way
  (based on RHEL6's checks/templates/create_package_installed.py),
* OVAL checks for ntp package installed and ntpd service enabled,
* and remediation for "ntpd service enabled" rule

Passed basic sanity && regression testing.

Please review.

Thank you && Regards, Jan.
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Jan iankko Lieskovsky / Red Hat Security Technologies Team