Remove the Makefile and files it uses

The Makefile build system was replaced by CMake, which uses a different approach to create the xml files for darwin and tunfold.

Closes #12 (closed). We can open a new issue for the jobs test if needed.

.gitlab-ci.yml

 image: gitlab-registry.cern.ch/ci-tools/ci-worker:cc7
 
 compilation:
-    stage: build
-    tags:
-        - cvmfs
-    script:
-        - source /cvmfs/cms.cern.ch/cmsset_default.sh
-        - yum install -y openssl-devel python3 zsh
-        - make
-
-cmake:
     stage: build
     tags:
         - cvmfs