Add a restorecon_recursive built-in command to init.

Functionally equivalent to the restorecon -R toolbox command.
A use case is given by:
I48eaa2b9901ac8c978192c14493ba1058a089423

Also, fix error handling and documentation for restorecon command.

Change-Id: Ia7fbcc82645baf52c6bff0490d3492f458881cbb
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
diff --git a/init/init_parser.c b/init/init_parser.c
index 2c2c91c..38582f5 100644
--- a/init/init_parser.c
+++ b/init/init_parser.c
@@ -133,6 +133,7 @@
     case 'r':
         if (!strcmp(s, "estart")) return K_restart;
         if (!strcmp(s, "estorecon")) return K_restorecon;
+        if (!strcmp(s, "estorecon_recursive")) return K_restorecon_recursive;
         if (!strcmp(s, "mdir")) return K_rmdir;
         if (!strcmp(s, "m")) return K_rm;
         break;