Revert "Disable parallel startup in interactive mode"

This reverts commit 8b4fc05ff2.
The original commit did not explain why this feature was disabled, and I
now have a request to enable it.

This fixes #24.

src/rc/rc.c

@@ -664,7 +664,6 @@ do_start_services(const RC_STRINGLIST *start_services, bool parallel)
 			interactive = want_interactive();
 
 		if (interactive) {
-			parallel = false;
 	interactive_retry:
 			printf("\n");
 			einfo("About to start the service %s",