syslog-ng: rewrite init script

- Rename it to S01syslog-ng to make every init script be called the same
  as the executable it starts.
- Indent with tabs, not spaces.
- Do not kill syslog-ng in "reload". Send a SIGHUP signal, instructing
  it to perform a re-initialization.
- Support a /etc/default/syslog-ng configuration file.

Signed-off-by: Carlos Santos <casantos@datacom.com.br>
Reviewed-by: Matt Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>