travis config, editorconfig and update gitignore for coverage files

Author: Josh-G

.editorconfig

@@ -0,0 +1,8 @@
+[*]
+indent_style = space
+indent_size = 4
+root = true
+
+[*.yml]
+indent_style = space
+indent_size = 2

.gitignore

@@ -1,2 +1,4 @@
 vendor
 composer.lock
+coverage-html
+coverage.xml

.travis.yml

@@ -0,0 +1,16 @@
+language: php
+
+php:
+  - '7.1'
+  - '7.2'
+  - '7.3'
+
+before_script:
+  - travis_retry composer self-update
+  - travis_retry composer install --no-interaction --prefer-source --dev
+
+script:
+  - vendor/bin/phpunit -c phpunit.xml --coverage-clover=coverage.xml
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)