Release process: use Travis for CI

[bzz]

Right now we use Drone for both, CI and CD.

We would like to use Travis for building and CI, as it is with other projects and Drone only for CD.
Drone could either pull or be pushed by Travis to trigger the deployment \w appropriate artefacts.

[dpordomingo]

The CD of this project was based on Landing/Blog/Talks CD system, which uses drone.io for deploying and releasing (delivering things)
I heard to @rporres that we could move everything to Travis (also the deploy process) so it could be great if we do everything at the same time.

[smacker]

@dpordomingo from my understanding this issue tries to decouple release process with deploying process. Which makes sense. We can deploy without release or release without deploy or change any of those implementations independently. Code annotation is different from Landing/Blog/Talks. Those 3 are src-d specific and aren't useful without deployment in our infrastructure. Code annotation has value outside of src-d. It can be used and deployed by anybody.

But whatever.

[rporres]

What @bzz states in this issue is totally valid. We started using Drone at the time for reasons that don't apply anymore (secrets potentially leaking) so at some point it would be great to move everything to Travis

Another option is to build in Travis and let Drone wait for the image to be pushed but that is a hack that will certainly cause issues at some point