Fix setting groups via web ui

The template is generated incorrectly, so when form data are sent via
POST, it does not contain new values for groups to save.

Additionally, set the default value to none and make sure the code does
not take the value as a bad value.

pappl/system-webif.c

@@ -1421,15 +1421,15 @@ _papplSystemWebSecurity(
 
       if ((group = cupsGetOption("admin_group", num_form, form)) != NULL)
       {
-        if (getgrnam_r(group, &grpbuf, buffer, sizeof(buffer), &grp) || !grp)
+        if (strcmp(group, "") && (getgrnam_r(group, &grpbuf, buffer, sizeof(buffer), &grp) || !grp))
           status = _PAPPL_LOC("Bad administration group.");
 	else
 	  papplSystemSetAdminGroup(system, group);
       }
 
       if ((group = cupsGetOption("print_group", num_form, form)) != NULL)
       {
-        if (getgrnam_r(group, &grpbuf, buffer, sizeof(buffer), &grp) || !grp)
+        if (strcmp(group, "") && (getgrnam_r(group, &grpbuf, buffer, sizeof(buffer), &grp) || !grp))
         {
           status = _PAPPL_LOC("Bad print group.");
 	}
@@ -1471,7 +1471,7 @@ _papplSystemWebSecurity(
     papplClientHTMLPrintf(client,
 			  "          <table class=\"form\">\n"
 			  "            <tbody>\n"
-			  "              <tr><th><label for=\"admin_group\">%s:</label></th><td><select name\"admin_group\"><option value=\"\">%s</option>", papplClientGetLocString(client, _PAPPL_LOC("Admin Group")), papplClientGetLocString(client, _PAPPL_LOC("None")));
+			  "              <tr><th><label for=\"admin_group\">%s:</label></th><td><select name=\"admin_group\"><option value=\"\">%s</option>", papplClientGetLocString(client, _PAPPL_LOC("Admin Group")), papplClientGetLocString(client, _PAPPL_LOC("None")));
 
     setgrent();
     while ((grp = getgrent()) != NULL)
@@ -1481,7 +1481,7 @@ _papplSystemWebSecurity(
 
     papplClientHTMLPrintf(client,
 			  "</select></td></tr>\n"
-			  "              <tr><th><label for=\"print_group\">%s:</label></th><td><select name\"print_group\"><option value=\"\">%s</option>", papplClientGetLocString(client, _PAPPL_LOC("Print Group")), papplClientGetLocString(client, _PAPPL_LOC("None")));
+			  "              <tr><th><label for=\"print_group\">%s:</label></th><td><select name=\"print_group\"><option value=\"\">%s</option>", papplClientGetLocString(client, _PAPPL_LOC("Print Group")), papplClientGetLocString(client, _PAPPL_LOC("None")));
 
     setgrent();
     while ((grp = getgrent()) != NULL)