Consider publishing a docker image to dockerhub

[jdufresne]

It would be convenient if a docker image containing the Airbrake CLI was publicly available. This image could track the current release. This could then be pulled down and used as an alternative to downloading the tar file. This kind of thing is especially useful in a CI environment. Thanks for considering.

[rbg]

Take the next step and provide that image as part of a github workflow :) FiF FTW.