Merge branch 'bugfix/gitlab-ci' into 'develop'

BUGFIX: Set default gitlab-ci image (alpine) & switch commands

See merge request !68

.gitlab-ci.yml

@@ -1,4 +1,4 @@
-image: 'php:latest'
+image: 'bash:latest'
 
 before_script:
   - apk add --no-cache make wget git
@@ -13,11 +13,12 @@ stages:
 sync:github:
   stage: sync
   before_script:
-    - apt-get -y update && apt-get -y upgrade
-    - apt-get -y install openssh-client git
+    - apk add --no-cache openssh-client git
     # SSH deploy key
     - eval $(ssh-agent -s)
-    - ssh-add <(echo "$SSH_PRIVATE_KEY")
+    - echo "$SSH_PRIVATE_KEY" > /tmp/private_key
+    - chmod go-rwx /tmp/private_key; chmod u-x /tmp/private_key
+    - ssh-add /tmp/private_key
     - mkdir -p ~/.ssh
     - '[[ -f /.dockerenv ]] && echo -e "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config'
   script: