(#7911) Added support for managing local users and groups when duplicate names exist in remote NSS database  e.g. LDAP

This patch addresses an issue where some applications may require a local user/group.  If the same account exists in LDAP or some other NSS the useradd and groupadd commands will not create the group locally because Ruby's Etc module will see the account in ldap and say it already exists.  In order to get the account to be created locally, luseradd or lgroupadd can be used in conjunction with a libuser.conf file that specifices the use of files and shadow. It's a way around nsswitch.conf which is what the Etc module uses.