Add CircleCI (#34)

Author: Ekman

.circleci/config.yml

@@ -0,0 +1,17 @@
+version: 2.1
+executors:
+  default:
+    docker:
+      - image: cimg/php:7.0
+      - image: cimg/php:7.1
+      - image: cimg/php:7.2
+      - image: cimg/php:7.3
+      - image: cimg/php:7.4
+orbs:
+  php-coveralls: nekman/php-coveralls@0.0.1
+  php-cs-fixer: stockfiller/php-cs-fixer@0.0.10
+workflows:
+  foo:
+    jobs:
+      - php-coveralls/test_and_upload
+      - php-cs-fixer/fix