Merge branch 'decode_ssh_key' into 'master'

Decode ssh key from bas64 such that we can store the key as a masked variable

See merge request !20

.gitlab-ci.yml

@@ -4,7 +4,7 @@ stages:
 before_script:
   - apk update && apk add git
   - eval $(ssh-agent -s)
-  - echo "$SSH_PRIVATE_KEY_PROJECT" | tr -d '\r' | ssh-add -
+  - echo "$SSH_PRIVATE_KEY_PROJECT" | base64 -d | tr -d '\r' | ssh-add -
   - mkdir -p ~/.ssh/ && ssh-keyscan git.astron.nl > ~/.ssh/known_hosts
   - git checkout "$CI_COMMIT_REF_NAME" # make sure the branch is checked out
   - git config user.email $GITLAB_USER_EMAIL