API documentation outdated

[dirkweissenborn]

we need API documentation that should at best be automatically generated whenever changes to master occur and hosted somewhere but (I think) it should not be part of the git repo.

[TimDettmers]

We can already generate those with sphinx and we could host them on https://readthedocs.org/. There is probably also github integration for that.

[riedelcastro]

That sounds great! Should be easy to add a wercker hook for this.