sslh: update to 1.20

sslh: update to 1.20

- New user and group sslh has been added.
- Added USELIBCAP to make transparent mode possible.
- red.up script has been added. If red IP changes, sslh will be restarted to run with the new IP.
- red.up script searches for sslh symlink in rc3.d, if nothing can be found, it will not start so it can be disabled via WUI (services.cgi).
- Symlinks for runlevels has been nevertheless added to sslh package to control it also via services.cgi.
- Configuration block has been added to sslh initscript.
- External IP address check will also be used for configure options.
- Configure provides currently only OpenVPN
- OpenVPN port will be automatically investigated.

Signed-off-by: Erik Kapfer <ummeegge@ipfire.org>