Add a Drone Cloud build

[vielmetti]

because I can, get Drone Cloud to do a build similar to the Travis build.

[vielmetti]

for instance, http://plugins.drone.io/cbrgm/drone-hugo/

[vielmetti]

success of a sort, but lots of

WARN 2019/02/03 08:05:17 Found no layout for "page", language "en", output format "HTML": create a template below /layouts with one of these filenames: baseball/single.en.html.html, baseball/single.html.html, baseball/single.en.html, baseball/single.html, _default/single.en.html.html, _default/single.html.html, _default/single.en.html, _default/single.html

[vielmetti]

Mostly this is a failure of me to understand what's going on, so let's remove Drone entirely and redo it from scratch.

[vielmetti]

Drone removed for now; bring it back as a linter.