MINOR: server: implement init-addr none

The server is put into the "no address" maintenance state in this case.
diff --git a/src/server.c b/src/server.c
index b4d4f50..b996914 100644
--- a/src/server.c
+++ b/src/server.c
@@ -1182,8 +1182,11 @@
 					else if (!strcmp(p, "last")) {
 						done = srv_append_initaddr(&newsrv->init_addr_methods, SRV_IADDR_LAST);
 					}
+					else if (!strcmp(p, "none")) {
+						done = srv_append_initaddr(&newsrv->init_addr_methods, SRV_IADDR_NONE);
+					}
 					else {
-						Alert("parsing [%s:%d]: '%s' : unknown init-addr method '%s', supported methods are 'libc', 'last'.\n",
+						Alert("parsing [%s:%d]: '%s' : unknown init-addr method '%s', supported methods are 'libc', 'last', 'none'.\n",
 							file, linenum, args[cur_arg], p);
 						err_code |= ERR_ALERT | ERR_FATAL;
 						goto out;
@@ -3255,6 +3258,10 @@
 			return_code |= err_code;
 			break;
 
+		case SRV_IADDR_NONE:
+			srv_set_admin_flag(srv, SRV_ADMF_RMAINT, NULL);
+			return return_code;
+
 		default: /* unhandled method */
 			break;
 		}