[Enhancement] [RHEL/6] Enable GUI Warning Banner:
* change OVAL id to start using 'gconf_...' prefix,
* couple of OVAL check cosmetic changes (indentation fixes, test_attestation update etc.),
* change rule ID in XCCDF & profile references to use the OVAL one,
* add remediation
[Enhancement] [RHEL/6] Set GUI Warning Banner Text:
* update OVAL check ID to start using 'gconf_'... prefix,
* couple of OVAL check cosmetic changes (change title & description
  they not to be copied from 'Enable GUI Warning Banner' check, update
  test_attestation etc.),
* change rule ID in XCCDF & profile references to use the OVAL one,
* add remediation
[Enhancement] [RHEL/6] Disable the User List:
* change the OVAL check ID to follow 'gconf_gdm' template,
* couple of OVAL check changes (replace old id with new one, update
  test_attestation etc.),
* change rule ID in XCCDF to use the OVAL one (doesn't seem to be
  referenced in RHEL-6 profiles => no profiles change needed),
* add remediation
Merge pull request #335 from iankko/rhel6_gconf_remediations_round_two

[Enhancement] [RHEL/6] RHEL-6 gconf rule's remediations round two