Add GitLab CI

• Different set of boxes, there isn't a 7.2 in the current series and doesn't seem like that'll changes
• Correct PHPUnit version for PHP version, as Travis handles

Fixes #2 (closed)

.gitlab-ci.yml

@@ -12,6 +12,8 @@ before_script:
 
   # install the required packages for the running CI tests
   - |
+    lsb_release -a
+
     apt-get -yqqf install zip unzip subversion mysql-client --fix-missing
 
     if [[ $(lsb_release -a) =~ "stretch" ]]; then