Updated no_shelllogin_for_systemaccounts to reflect RHEL7 UIDs starting at 1000
Renamed accounts_password_pam_cracklib_retry.xml --> accounts_password_pam_retry, updated for RHEL7

- Renamed XCCDF/OVAL to accounts_password_pam_retry to reflect requirement (pam retry) vs implimentation
- Updated OVAL to include conditional check of OS, then will check either cracklib or pwquality
Updated installed_OS_is_rhel7

Updated state/object names as when performing "if rhel6; do something; elseif rhel7" you receive naming collisions
Updated accounts_password_pam_retry XCCDF & relinked OVAL into RHEL/7/shared
Resolving installed_os_rhel7 merge conflicts
Merge branch 'accounts_password_pam_cracklib_retry' of https://github.com/shawndwells/scap-security-guide into shawndwells-accounts_password_pam_cracklib_retry

Merging for PR #246

https://github.com/OpenSCAP/scap-security-guide/pull/246#issuecomment-57023999
Merge branch 'shawndwells-accounts_password_pam_cracklib_retry'

Merge for PR 246

https://github.com/OpenSCAP/scap-security-guide/pull/246#issuecomment-57023999