Refactor TTY code to honor runlevels and use I/O plugin to watch /dev

Add support for runlevels to tty command and support for reading baud
rate and TERM variable from finit.conf.

The tty-watcher thread has been converted to a standard I/O plugin.

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

finit.c

@@ -34,6 +34,7 @@
 #include "plugin.h"
 #include "svc.h"
 #include "sig.h"
+#include "tty.h"
 #include "lite.h"
 
 int   debug     = 0;
@@ -273,7 +274,7 @@ int main(int argc, char* argv[])
 	plugin_run_hooks(HOOK_SYSTEM_UP);
 
 	/* Start GETTY on console(s) */
-	tty_start();
+	tty_runlevel(runlevel);
 
 	/*
 	 * Enter main loop to monior /dev/initctl and services