luci-app-qbittorrent: tidy up code (coolsnowwolf#8194)

Version Update to R20.9.15

luci-app-ssr-plus: OpenWrt SNAPSHOT compatibility (coolsnowwolf#4154)

* luci-app-ssr-plus: OpenWrt SNAPSHOT compatibility

Fix coolsnowwolf#4143

* Modify getElementById to getElementsByName

Luci modification for OpenWrt 19.07 or higher