New approach to build conan docker images

conan-el6-gcc44-x86/Dockerfile

conan-el6-gcc44/Dockerfile

conan-el6-gcc73-x86/Dockerfile

conan-el6-gcc73/Dockerfile

conan-el6-gcc83-x86/Dockerfile

conan-el6-gcc83/Dockerfile

conan-el6-gcc91-x86/Dockerfile

conan-el6-gcc91/Dockerfile

conan-el7-gcc48-x86/Dockerfile

conan-el7-gcc48/Dockerfile

conan-el7-gcc73-x86/Dockerfile

conan-el7-gcc73/Dockerfile

conan-el7-gcc82-x86/Dockerfile

conan-el7-gcc83/Dockerfile

conan-el7-gcc93-x86/Dockerfile

conan-el7-gcc93/Dockerfile

dependencies.dot