Improved Librarian init script

- Fixes init script not being able to stop the service
- Fixes status reporting
- Presents messages that are in line with other Debian init scripts

Fixes #9
Factored out XBMC-related parts of the install script

The new script (`xmbc.sh`) is still untested (and pretty much guaranteed
to fail).

See #11
Use update-rc.d instead of setting x flag
Add note about TVHeadend configuration

This is probably a better solution than trying to set anything for the
user.

Fixes #10