[bugfix]  Modified verify-references.py to reflect 800-53 rev4
[bugfix] - sshd_disable_root_login OVAL false positive

- fix false positive for PermitRootLogin check in sshd_config
system auth password hashing algorithm can also be required

Updated OVAL code to also accept required, in addition to 'sufficient'
resubmit - Updated Smart Card XCCDF to reflect SSH+CAC docs

- Added link to vendor docs
- bolded links
- "CAC cards" was redundant