[Enhancement] move compatible OVAL checks to the shared directory

- Move compatible Fedora checks to the shared directory
- Share no_netrc_files OVAL check and enable for RHEL 6 & 7 and Fedora
- Share securetty OVAL checks and enable for RHEL 6 & 7 and Fedora
- Add Fedora 20 OVAL check
[Enhancement] [RHEL/6] Add audit DAC remediations for chmod, fchmod & fchmodat system calls
[Enhancement] [RHEL/6] Add audit DAC remediations for chown group based system calls
                       (chown, fchown, lchown & fchownat)
[Enhancement] [RHEL/6] Add audit DAC remediations for xattr group based system calls
(setxattr, lsetxattr, fsetxattr, removexattr, lremovexattr, and fremovexattr)
Merge pull request #337 from redhatrises/shared_fedora_updates

[Enhancement] move compatible OVAL checks to the shared directory
Merge pull request #340 from iankko/audit_syscall_group_remediations

[Enhancement] [RHEL/6] Add audit syscall remediations for '*chown*, *chmod* & *xattr' groups