Fixed vhostsubdomain not empty regex check to allow 1 char subdomains.

Till Brehm

2014-02-17 baa7f2736bc91ca3feaed685e8a67a46db4fbb98

 server/scripts/ispconfig_update.php

@@ -100,7 +100,7 @@
      echo "There are no updates available for ISPConfig ".ISPC_APP_VERSION."\n";
   }
} else {
   passthru('/usr/local/ispconfig/server/scripts/update_from_svn.sh');
   passthru('/usr/local/ispconfig/server/scripts/update_from_dev.sh');
   exit;
}