Automated travis docker testing and deploys. (#1023)

Automated travis docker testing and deploys. (#1023)

* Testing out a travis 1.

* Testing out a travis 2.

* Testing out a travis 3.

* Testing out a travis 4.

* Testing out a travis 5.

* Testing out a travis 6. Trying a failing test

* Testing out a travis 7. Trying to cache the docker images.

* Testing out a travis 8. Still not correctly failing.

* Trying full path for docker_images dir.

* Fixing test again, trying a dockerhub deploy.

* Fixing test again, trying a dockerhub deploy 2.

* Remove caching.

* Trying to fix docker deploy.

* Try using the travis tag

* Using dessalines/lemmy:travis

* Try using the prod dockerfile now.

* Update http sigs dependency

* Finally getting this mostly working.

Co-authored-by: asonix <asonix@asonix.dog>