Add CI improvements

Author: claudiodekker

.editorconfig

@@ -0,0 +1,15 @@
+; This file is for unifying the coding style for different editors and IDEs.
+; More information at https://editorconfig.org
+
+root = true
+
+[*]
+charset = utf-8
+indent_size = 4
+indent_style = space
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.md]
+trim_trailing_whitespace = false

.gitattributes

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+# Path-based git attributes
+# https://www.kernel.org/pub/software/scm/git/docs/gitattributes.html
+
+# Ignore all test and documentation with "export-ignore".
+/.editorconfig      export-ignore
+/.gitattributes     export-ignore
+/.gitignore         export-ignore
+/.styleci.yml       export-ignore
+/.scrutinizer.yml   export-ignore
+/.travis.yml        export-ignore
+/phpunit.xml.dist   export-ignore
+/tests              export-ignore

.styleci.yml

@@ -0,0 +1 @@
+preset: laravel

.travis.yml

@@ -0,0 +1,31 @@
+sudo: required
+
+language: php
+
+php:
+  - 5.4
+  - 5.5
+  - 5.6
+  - 7.0
+  - 7.1
+  - 7.2
+  - 7.3
+  - 7.4
+
+env:
+  matrix:
+    - COMPOSER_FLAGS="--prefer-lowest"
+    - COMPOSER_FLAGS=""
+
+before_install:
+  - travis_retry composer self-update
+
+install:
+  - travis_retry composer update --prefer-source $COMPOSER_FLAGS
+
+script:
+  - phpunit
+
+branches:
+  only:
+    - master