Additional Options/Functionality

Our organization has a need for configuring SSSD/SSSD Auth in conjunction with LDAP.  In RHEL 6 SSSD is now the default local caching of user related information.  Working in concert with the above, is the 'forcelegacy' option, which helps setup the SSSD service in the sssd.conf, nsswitch.conf, and system-auth files.  The pam_access piece was added as our organization uses this in conjunction with access.conf for an added layer of access control.

This pull request includes 4 additional options and an update to the README with a brief description of each option's intended purpose.