[Feature request] WebDAV data backup

[stokito]

It's possible to save the playlist to remoteStorage server and that's great. But maybe for most users just a plain WebDAV will work just fine.
In my case I have a router with OpenWrt and I installed Lighttd+mod_dav.
But for the remoteStorage I had to install armadietto with Node.JS and NPM (about 30mb). And it wasn't easy.
This solved my problem but to make it easier for others it would be great to just support the backup to WebDAV.

This was also requested by @justicenode #88 (comment)

It also possible another way: implement the WebDAV storage backend on the remotestorage.js level remotestorage/remotestorage.js#1093

[icidasset]

Thanks for the request! I think it makes sense to implement this at some point 👍