Change the Docker images names pattern
After the merge of #161 (closed) stable and LTS branches will still need CI.
That said, it is necessary to append to the Docker image tag some information about the version of SpiderMonkey that it provides. It should be:
SM52-gcc.fedora-dev
| | | |_ Fedora Devel (Rawhide)
| | |_ Fedora
| |_ compiled using gcc
|_ SpiderMonkey 52
Other examples
- SM60-gcc.fedora-dev (SpiderMonkey 60)
- SM52-gcc.fedora-dev.ppc64le (non x86_64)
- SM52-gcc.ubuntu-lts (Ubuntu LTS)