[RHEL/7][Fedora] Update IPv6 Kernel Module to sysctl setting

- Migrate IPv6 kernel module disable to sysctl settings
- Enabled for Fedora
- Fixes #60
[RHEL/7] add Sysctl IPv6 Kernel check
[Enhancement] Add initial list of Contributors
Merge pull request #301 from redhatrises/contributors

[Enhancement] Add initial list of Contributors
[RHEL/6, RHEL/7] Fix XCCDF description of (the three per each product) pam_faillock
                 rules so they would be based on the complete second example from the
                 pam_faillock manual page (fixes #302 issue)
[shared] Fix remediation script for 'Set Deny For Failed Password Attempts' issue wrt to
         problems noted in issue #304.
Merge pull request #303 from iankko/rhel6_rhel7_pam_faillock_drop_authsucc_add_preauth_calls

[RHEL/6, RHEL/7] Fix pam_faillock rules recommendations so they wouldn't be thrown out of context
[shared] Fix indentation for accounts_passwords_pam_faillock_deny remediation script yet
         (so it would align with other rows in /etc/pam.d/{password,system}-auth files)
Merge pull request #305 from iankko/shared_fix_accounts_passwords_pam_faillock_deny_remediation

[bugfix] [shared] Fix remediation script for 'Set Deny For Failed Password Attempts wrt to issue #304
Merge pull request #300 from redhatrises/kernel_ipv6_sysctl

[RHEL/7][Fedora] Update IPv6 Kernel Module to sysctl setting