simple circleci.com px4_fmu-v5 build & archive example

[dagar]

We don't need this in PX4/Firmware, but it serves as a nice simple example for both public and private forks. Circleci is one of the only continuous integration services that has a free tier for private projects, so having this in tree (and maintained) makes it trivial to get started.

FYI @LorenzMeier @julianoes @mrpollo @hamishwillee

[hamishwillee]

Does it need docs? Ie perhaps a page "Circle CI" in http://dev.px4.io/master/en/test_and_ci/ ?

I don't know enough to write that, but if you can bullet point what you'd like to say ....

[dagar]

It's not high priority or anything, but it might be worth a quick mention in the Dev guide that it only takes a few clicks/seconds to have your own personal/private build system going. It's for anyone with their own fork of PX4 (public or private) that typically wouldn't bother setting up this kind of thing (small companies, students, researchers, etc).

To use it you just login to Circleci via github (https://circleci.com/), point it at your repo (PX4/Firmware fork) and it will start building and storing px4_fmu-v5_default binaries using our docker containers. You could try this yourself with a fork.