Extend automatic docker build

[lfoppiano]

This PR will extend the docker build so that:

• both the CRF and the delft full image are built and pushed at each commit using tag latest-develop and latest-develop-crf. Such built are limited to master and PRs (branch for which a PR has been opened)
• Add an additional github action that can be triggered manually, to build and push both CRF and delft image of any branch selected by the user

[coveralls]

coverage: 39.903%. remained the same
when pulling 22b9e6a on extend-docker
into be9e652 on master.

[lfoppiano]

As discussed, I've removed the docker build of the full image from the automatic build (which will build only the CRF image). The full image could be still built manually from the github actions.