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

@@ -14,6 +14,7 @@ before_script:
   - apt-get -yqqf install zip unzip subversion mysql-client default-libmysqlclient-dev --fix-missing
 
   # PHP extensions
+  - docker-php-ext-install mbstring mcrypt mysqli pdo_mysql intl gd zip bz2
   - docker-php-ext-enable mbstring mcrypt mysqli pdo_mysql intl gd zip bz2
 
   # Install Composer
@@ -37,6 +38,7 @@ PHPunit:PHP5.3:MySQL:
     - php composer.phar global require "phpunit/phpunit=4.8.*"
     - phpcs
     - phpunit
+  allow_failure: true
 
 PHPunit:PHP5.6:MySQL:
   image: php:5.6-stretch