Add travis file

.travis.yaml

@@ -0,0 +1,26 @@
+language: php
+php:
+  - '5.4'
+  - '5.5'
+  - '5.6'
+  - '7.0'
+  - '7.1'
+  - '7.2'
+  - '7.3'
+
+cache:
+  directories:
+    - $HOME/.composer/cache
+
+before_install:
+  - travis_retry composer self-update
+
+install:
+  - travis_retry composer install --no-interaction --prefer-dist --no-suggest
+
+script:
+  - vendor/bin/phpunit --coverage-text --coverage-clover=coverage.clover
+
+after_script:
+  - wget https://scrutinizer-ci.com/ocular.phar
+  - php ocular.phar code-coverage:upload --format=php-clover coverage.clover