Resolve "Init String calculator project"

Closes #11 (closed)

stringCalculator/.gitlab-ci.yml

+stages:
+  - build
+  
+package-roman-numerals:
+  extends: .java
+  stage: build
+  tags:
+    - docker
+  script:
+    - cd stringCalculator
+    - mvn $MAVEN_CLI_OPTS clean package
+    - cat target/site/jacoco/index.html
+  artifacts:
+    reports:
+      junit: stringCalculator/target/surefire-reports/TEST-*.xml
+    expire_in: 1 day
+  only:
+    refs:
+      - master
+      - merge_requests
+    changes:
+      - ".gitlab-ci.yml"
+      - ".gitlab-common-ci.yml"
+      - "stringCalculator/**/*"