Add ldap username field option. Default field is 'cn'

lib/cli.js

@@ -360,6 +360,10 @@ program
     , 'LDAP search field (or $LDAP_SEARCH_FIELD)'
     , String
     , process.env.LDAP_SEARCH_FIELD)
+  .option('--ldap-username-field <scope>'
+    , 'LDAP username field (or $LDAP_USERNAME_FIELD)'
+    , String
+    , process.env.LDAP_USERNAME_FIELD || 'cn')
   .action(function(options) {
     if (!options.secret) {
       this.missingArgument('--secret')
@@ -386,6 +390,9 @@ program
         , objectClass: options.ldapSearchClass
         , field: options.ldapSearchField
         }
+      , username: {
+          field: options.ldapUsernameField
+        }
       }
     })
   })