added mirror ci for gitlab (#175)

.gitlab-ci

+image: ubuntu:18.04
+
+clone_github:
+    stage: deploy
+    before_script:
+        - apt-get update -y && apt-get install openssh-client -y
+        - apt install git -y
+        - eval $(ssh-agent -s)
+        - echo "$GIT_SSH_PRIVATE_KEY" | openssl base64 -A -d | ssh-add -
+        - mkdir -p ~/.ssh
+        - chmod 700 ~/.ssh
+        - ssh-keyscan $GIT_LAB_HOST >> ~/.ssh/known_hosts
+        - chmod 644 ~/.ssh/known_hosts
+        - git config --global user.name "${GIT_USER_NAME}"
+        - git config --global user.email "${GIT_USER_EMAIL}"
+        - ssh "git@$GIT_LAB_HOST"
+    script:
+        - echo $SOURCE_REPOSITORY
+        - git config --global http.sslVerify false 
+        - rm -rf plio 
+        - git clone --mirror $SOURCE_REPOSITORY plio
+        - cd plio
+        - git remote remove origin
+        - git remote add origin $DESTINATION_REPOSITORY
+        - git push -f --prune --all
+        - git push -f --prune --tags
+    only:
+        - branches