New images naming convention and fix build with buildah

.gitlab-ci.yml

dependencies.dot

dev-el6-gcc44-x86/.gitlab-ci.yml

dev-el6-gcc44-x86/Dockerfile

dev-el6-gcc44/.gitlab-ci.yml

dev-el6-gcc7-x86/.gitlab-ci.yml

dev-el6-gcc7-x86/Dockerfile

dev-el6-gcc7-x86/docker-compose.yml

dev-el6-gcc7/.gitlab-ci.yml

dev-el6-gcc7/Dockerfile

dev-el6-gcc7/docker-compose.yml

dev-el6-gcc73-x86/.gitlab-ci.yml

dev-el6-gcc73/.gitlab-ci.yml

dev-el6-gcc73/docker-compose.yml

dev-el6-gcc8-x86/.gitlab-ci.yml

dev-el6-gcc8-x86/Dockerfile

dev-el6-gcc8-x86/docker-compose.yml

dev-el6-gcc8/.gitlab-ci.yml

dev-el6-gcc8/Dockerfile

dev-el6-gcc8/docker-compose.yml