emms-listenbrainz-scrobbler

I have just added a branch to the repo called listenbrainz.

It contains emms-listenbrainz-scrobbler.el which scrobbles to
listenbrainz.org along with a node about it in emms.texinfo.

This may be too niche for inclusion in the distribution but you are welcome
to it if you want it!

---Fran