Add Travis CI configuration

.travis.yml

@@ -0,0 +1,33 @@
+language: php
+
+php:
+  - 5.5
+  - 5.6
+  - 7.0
+  - 7.1
+  - 7.2
+  - 7.3
+  - nightly
+
+matrix:
+  allow_failures:
+    - php: nightly
+  fast_finish: true
+
+cache:
+  directories:
+    - $HOME/.composer/cache
+
+install:
+  - travis_retry composer update --no-interaction --no-progress --no-suggest --prefer-dist
+
+script:
+  - composer test
+
+after_script:
+  - |
+    if [[ ${TRAVIS_PHP_VERSION:0:3} == "7.2" ]]
+    then
+      travis_retry wget --no-verbose https://scrutinizer-ci.com/ocular.phar
+      php ocular.phar code-coverage:upload --format=php-clover build/clover.xml
+    fi