test: added travis.yml

Author: mle86

.travis.yml

@@ -0,0 +1,20 @@
+language: php
+
+php:
+# - '5.6'
+  - '7.0'
+  - '7.1'
+  - '7.2'
+
+before_install:
+  - composer self-update
+
+install:
+  - composer install
+
+script:
+  - make test
+
+after_success:
+  - travis_retry php vendor/bin/php-coveralls
+