Add attributes.tld for TravisCI badge

[kpp]

Issue: #1392

Idea from https://github.com/livioribeiro/cargo-readme/pull/29/files:

[badges]
travis-ci = { repository = "tox-rs/tox", tld = "com" }

Is there a parser for attributes where I can check whether tld equals to "org" or "com"?

How do I write tests for js renderer to make sure there are only travis-ci.org/com domains?

[kpp]

@carols10cents I need help.

[pietroalbini]

I'd mark this as blocked until we have an answer for #1392 (comment).

[kpp]

We talked with our contacts at Travis CI, and they're looking into providing an unified badges URL regardless of the tld.

Thanks!

[carols10cents]

Travis is in the process of providing automatic redirects. Closing!

[kpp]

Yep. Hence https://travis-ci.com/kpp/futures-async-combinators and https://api.travis-ci.org/kpp/futures-async-combinators.svg?branch=master