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>
(cherry picked from commit a9443eb0eb)
Tested-by: Marc Benoit <marcb62185@gmail.com>

utils/syncthing/Makefile

@@ -2,7 +2,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=syncthing
 PKG_VERSION:=1.4.0
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=syncthing-source-v$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://github.com/syncthing/syncthing/releases/download/v$(PKG_VERSION)
@@ -32,6 +32,7 @@ define Package/syncthing
   DEPENDS:=$(GO_ARCH_DEPENDS)
   SECTION:=utils
   CATEGORY:=Utilities
+  USERID:=syncthing:syncthing
 endef
 
 GO_PKG_LDFLAGS_X:=\