Couple new features for PCDM
1) Add option to require that the user type in the username instead of just selecting one from a list (does not recognize "root" or "toor", I made sure of that)
2) Move the backend system user detection to using "getent" after conversation with john @ ixsystems. That should properly pick up LDAP/ActiveDirectory users as well, whereas "pw" might not.
Merge branch 'master' of github.com:pcbsd/pcbsd