Use default port for thin

No reason to use non-default
Update how thin starts and stops

Use long form options for clarity
Use thin’s built in start and stop mechanisms
Use thin’s built in process owner options
Bind to localhost only
Use thin’s built in restart command
Fix sysvinit case indentation
Exit gracefully from sysVinit if thin not available

> These scripts should not fail obscurely when the configuration files
> remain but the package has been removed, as configuration files remain
> on the system after the package has been removed. Only when dpkg is
> executed with the --purge option will configuration files be removed.
> In particular, as the /etc/init.d/package script itself is usually a
> conffile, it will remain on the system if the package is removed but
> not purged. Therefore, you should include a test statement at the top
> of the script, like this:
>
>    test -f program-executed-later-in-script || exit 0

https://www.debian.org/doc/debian-policy/ch-opersys.html#s-writing-init
Update sysvinit SITE_HOME, mute thin, etc

- Use SITE_HOME as full path to the app
- Mute thin output
- Return true from daemon commands
Add some progress reports to sysvinit

Follows nginx convention