Improve runlevel support by adding a bootstrap phase, also adds task/run cmd

Most systems need an early bootstrap phase for one-shot tasks and
necessary one-time probing.  This phase usually runs well before any
networking is setup.  This commit adds support for that 'S' runlevel,
and also extends the number of possible total runlevels to nine.

For the one-shot tasks that run in bootstrap two new finit.conf cmds
have been added:

   - task: For one-shot tasks that can be started in parallell
   - run:  For one-shot tasks that must run in sequence

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

plugins/initctl.c

@@ -91,10 +91,13 @@ static void parse(void *UNUSED(arg), int fd, int UNUSED(events))
 
 			case 's':
 			case 'S':
+				_d("Cannot enter bootstrap after boot ...");
 				rq.runlevel = '1';
 				/* Fall through to regular processing */
+
 			case '1'...'5':
-				_d("Setting new runlevel %c ...", rq.runlevel);
+			case '7'...'9':
+				_d("Setting new runlevel %c", rq.runlevel);
 				svc_runlevel(rq.runlevel - '0');
 				break;