[bugfix] [RHEL/7] Create services_disabled & services_enabled templates for RHEL-7 (based on unix:file_test & systemd-aware)

This set of patches does the following:
1) Updates former RHEL-6 services_disabled template to be systemd-aware using unix:file_test probe,
    Testing status: Tested on RHEL-7 & works as expected.

2) Unifies packages_removed RHEL-6 & RHEL-7 OVAL checks to be shared/ ones (since I needed it for subsequent changes) for the following services:
    * abrtd, sshd, atd, rdisc, oddjobd, qpidd

    Testing status: Tested on both RHEL-6 & RHEL-7 & (still) works fine.

3) Adds RHEL-7 specific package_removed OVAL check for ntpdate package (since there wasn't one for RHEL-6 yet that could be shared)

     Testing status: Tested on RHEL-7 & works fine.

4) Adds initial RHEL-7 specific content for services_disabled.csv file (make it to be aware of we want those seven services to be handled within it) & adds RHEL-7 specific OVAL checks for service disabled condition for those seven services (replaced former RHEL-7 service_sshd_disabled.xml version with the templated one)

     Testing status: Tested on RHEL-7 & works fine

5) Finally updates RHT-CCP profile to switch on rules for the following six services:
    * abrtd, atd, rdisc, ntpdate, oddjobd & qpidd
    Updates appropriate XCCDF test stamp entries for these services on RHEL-7 & also RHEL-7 test stamp entry for the sshd service.

     Testing status: Tested on RHEL-7 & works fine.

Please review (further testing appreciated, but generally AFAICT / as far as I tested this should be working correctly).

Thanks,  Jan.