syncthing: configuration cleanup & hardening

syncthing: configuration cleanup & hardening

Run the service under an unprivileged
user account

The following parameters are now configurable
  niceness
  max concurrency (defaults to number of CPUs)
  user

Added flags "-no-browser"
Disabled in-place upgrades (disabled in the
build already)

Redirected stderr/stdout to syslog

Added support for "reload_config"

Increased "term_timeout" to 15s to give it
plenty of time to shut down gracefully

Properly handled non-existing directories

Removed a softlink that assumes a specific naming
convention in syncthing

Added a comment that using external storage is a
recommend configration

Signed-off-by: Marc Benoit <marcb62185@gmail.com>
[increased package release]
Signed-off-by: Paul Spooren <mail@aparcar.org>