Point all the badges at proper branch for 1.9

That mostly matters for scrutinizer code coverage that varies a lot between branches as well as for the readthedocs build statuses. Unfortunately it only seems to take html build into account and doesn't indicate pdf build failures which I hoped for.

It looks like we should remember to update branches for current bugfix, 1.x and master to keep badges in context. Readthedocs pretty much gives away configured branch. I don't think we have checklist on creating new branches, so nothing to update at the moment.